ending through the body just below the spinal cord. In the lampreys, sharks, dipnoans, crossopterygians, and sturgeons the skeleton is still cartilaginous, but g

of the bones great importance in the systematic arrangement of these fishes. In fact the true affinities of forms is better shown by the bones than by any other system of organs. In a general way the ske

al with the humerus, coracoid, clavicle, radius, ulna, and carpus of the higher vertebrates. The vertebrate arm is not derived from the pectoral fin, but both from a c

ifferent ones have successively borne the names of scapula, clavicle, coracoid, humerus, radius, and ulna. None of these terms, unless it be clavicle, ought by rights apply to the fish, for no bone of the fish is a true homologue of any of these as seen in man. The land vert

s, Roccus lineatus (

ike forms (Branchiostoma) has no differentiated head or skull, but in all the other forms the anterior part of the vertebral column

general name of gnathostomes. In the sharks and their relatives (rays, chim?ras, etc.) all the skeleton is composed of cartilage. In the more specialized bony fishes, besides these bones we find also series of memb

lineatus. Latera

ipital. 13. Parasphenoid. 15. Prootic. 2. Ethmoid. 4. Frontal. 6. Parieta

ineatus. Superior

9. Pterotic. 11. Exoccipital. 2. Ethmoid. 4. Fron

ineatus. Inferior

13. Parasphenoid. 16. Alisphenoid. 3. Prefrontal. 5. Sphenotic.

s it will be more convenient to begin with a highly specialized form in w

nited States. For this set of plates, drawn from nature by Mrs. Chloe Lesley Starks, we are indebted to the courtesy of Mr. Edwin Chapin Starks. The fi

ior margin being usually a vertical knife-like edge. The pterotic (9) forms a sort of wing or free margin behind the epiotic and over the ear-cavity. The opisthotic (10) is a small, hard, irregular bone behind the pterotic. The exoccipital (11) forms a concave joint or condyle on each side of the basioccipital (12), by which the vertebral column is joined to the skull. The parasphenoid (13) forms a narrow ridge of the roof of the mouth, connecting the vomer with the basioccipital. In some fishes of primitive structure (Salmo, Beryx) there is another bone, called orbitosphenoid, on the middle line above and between the eyes. The basisphenoid (14) is a little bone above the myotome or tube in which runs the rectus muscle of the eye. It descends toward the parasphenoid and is attached to the prootic. The prootic (15) is an irregular bone below th

neatus. Posterior

arie

Epi

raocci

tero

pisth

xocci

siocci

ched to the cranium by membranes only, not by sut

angles with the rest of the bone into a groove on the ethmoid. There is often a fold in the skin by which this bone may be thrust out or protracted, as though drawn out of a

ry is divided by one or more sutures, setting off from it one or more extra maxillary (supplemental maxillary) bones. This suture is absent in the striped bass, but distinct in the black bass, and more than one suture is found in the shad and herring. The roof of the mouth above is formed by a number of bones, which, as they often possess teeth, may be considered with the jaws. These are the palatine bones (21), one on either side flan

ace-bones, shoulder and pel

omandi

ymple

Quad

Pter

Pala

sopter

tapter

reope

Oper

ubope

ntero

Arti

Angu

Dent

Maxi

remax

Inte

Epih

Cera

Basi

losso

Uroh

anchio

reorb

uborb

Na

pratem

st-tem

pracla

Clav

ostcl

percor

ypoco

Acti

ector

lvic g

entra

the quadrate, the whole forming the palato-quadrate apparatus. In the him?ra and the dipnoans this apparatus is so

Amia calva (Linn?us),

(28), which is connected by a joint to the quadrate bone (19). At the lower angle of the articular bone is the small angular bone (29). In many cases another small bone, which is called splenial, may be found attached to the inner surface of the articular bone. Thi

joins the cranium. The slender bone which thus keys together the upper and lower elements, hyomandibular and quadrate, forming the suspensorium of the lower jaw, is known as symplectic (18). The hyomandibular is thought to be homologous with the stapes, or stirrup-bone, of the ear in higher animals. In this case the symplectic may be homologous with its small orbicular bone, and the malleus is a transformation of the art

ection with the cranium. Such bones, formed of ossified membrane, are not found in the earlier or less specialized fishes, the lancelets and lampreys,

ary. Behind and below the eye is a series of about three flat bones, the suborbitals (50), small in the striped bass, but sometimes considerably modified. In the great group of loricate fishes (sculpins, etc.), the third suborbital sends a bony process called the suborbital stay backward across the cheek to

is the prominent ridge of the preopercle (24), which curves forward below and forms a more or less distinct angle, often armed with serrations

to important variations. In many fishes some of these bones are coossified, and in other cases some are wanting.

tinuous with it is the epihyal (34), to which behind is attached the narrow interhyal (33). On the under surface of the ceratohyal and the epihyal are attached the branchiostegals (39). These are slender rays supporting a membrane beneath the gills, seven in number on each side in the striped bass, but much more numerous in some groups of fishes.

esence of teeth, and very rarely having on it any of the gill-fringes. The fifth arch thus modified to serve in mastication

ries of basibranchials (40) which lie behind the epihyal of the tongue. On the three bones forming the first gill-arch are attached numerous appendages called gill-rakers (47). These gill-rakers vary very greatly in number and form. In the striped bass they are few and

eatus. Branchial ar

sibran

pobran

ratobr

pibra

ensory p

er phar

er phar

ill-r

he lower pharyngeals are most highly specialized and the most useful in classification. These are usually formed much as in the striped bass. Occasionally they are much enlarged, with large teeth for grinding. In many families the lower p

riped bass and in many of the higher fishes, but varying in different groups from 16 to 18 to upwa

ned backward, zygapophyses (71), and two larger ones, neurapophyses (67), which join above to form the neural

th of European Chub, Leuciscus c

als of a Parrot-fish, S

of a Parrot-fish, Scarus

hrough the h?mal canal thus formed passes a great artery. The vertebr? having h?mal as well as neural spines are known

those of the caudal vertebr?. In place, however, of the h?mapophyses are projections known as parapophyses (

an Parrot-fish, Sparisoma cre

e rather loosely attached and each rib may have one

al column and appendages, with a

ominal

udal v

Cent

urapop

eural

?mapo

?mal

ygapo

arapo

Ri

piple

ntern

orsal

nterh

Anal

Hypu

audal

and the catfish, 4 or 5 anterior vertebr? are greatly modified, coossified, and so arranged as to connect

uble concave (amplic?lian). In sharks the vertebr? are imperfectly ossified, a number of terms, asterospondylous, cyclospondylous, tectospondylous, being a

esh and not joined by ligament or suture. Below the dorsal fin (76) lies a series of these bones, dagger-shaped, with

, made hollow and quill-shaped, and in its concave upper end the tip of the air-bladder is received. This structure is seen in the plume-fishes (Calamus). These two g

fin, Holoptychius leptopteru

be heterocercal. In the isocercal tail of the codfish and its relatives the vertebr? are progressively smaller behind and the hypural plate is obsolete or nearly so, the vertebr? remaining in the line of the axis of the body and dividing the caudal fin equally.

girdle that the greatest confusion in names has occurred. This is due to an attempt to homologize its parts with the shoulder-girdle (scapula, coracoid, and clavicle) of higher vertebrates. But it is not evident that a bony fish possesses a real scapula, coracoid, or even clavicle. The parts of its shoulder-girdle

oral region of the cranium. Sometimes, as in the trigger-fishes, it is grown fast to the skull, but it usually rests lightly with the three points of its upper end. In sharks and skates the shoulder-girdl

sterotemporal) (54). To this is joined the long clavicle (proscapula) (55), which runs forward and downward in the bony fishes, meeting its fellow on the opposite side in a manner suggesting the wishbone of a fowl. Behind the base of the clavicle, the sword-shaped post-clavicle (56) extends downward through the muscles behind the base of the

Buffalo-fish, Ictiobus bubalus Rafinesque, s

er fishes only and not in the higher vertebrates, they should receive names not used for other structures. The hypercoracoid is usually pierced by a round foramen or fenestra, but in some fishes (cods, weavers) the fenestra is between the two bones. Attached to the hypercoracoid in the striped bass are

uch elongated, forming a kind of arm, by which

es, however, these bones are well differentiated and distinct. In most of the soft-rayed fishes an additional V-shaped bone or arch exists on the inner surface of the shoulder-girdle

hryne tumida (Osbeck). One of t

of Sebastolobus alascanus

ost-te

Clav

ostcla

yperco

Hypoco

ventral fin (63) is articulated to a single

bastolobus alascanus G

Vom

Nas

Eth

refro

Fron

arasph

Alisp

arie

asisp

Pro

siocci

praocc

xocci

Epi

Sphen

Pte

ery close to the clavicle, but not connected with it, as in the mullet, the fin is still said to be abdominal or subabdominal. In the striped bass the pelvis is joined by ligament between the clavicles, near their tip. The ventral fins thus connected, as seen in most spiny-rayed fishes, are said to be thoracic. In certain forms the pelvis is thrown still farther f

alate of Sebastolobus al

Pala

Mesopt

Pter

etapte

Den

Arti

Angu

uadr

ymple

omandi

Preop

nterop

Subop

Oper

n loses its complexity it is said to be degenerate. If in the geological history of a type the same change takes place the same term is used. Degeneration in this sense is, like specialization, a phase of adaptation. It

hes, those in which the bony framework has attained completion. But to understand the origin and relation of part

lary of Sebastolobus alascanus.

fish to the other, and pointed at both ends, no skull being developed. The notochord never shows traces of segmentation, alth

skeleton of Selen

lostomi (lampreys and hagfishes) the limbs and lower jaw are still wanting, but a distinct skull is developed. The notochord is still present, but its anterior pointed end is wedged into the base of a cranial capsule, partly membranous, partly cartilaginous. There is no trace of segmentation in the notochor

scyllium indicum, a Scyliorhinoid

ndicus (Gmelin), a notidanoid sh

ectoral fin of Monkfish,

the skull in the shark is attached a suspensorium of one or two pieces supporting the mandible and the hyoid structures. In the chim?ra the mandible is articulated directly with the skull, the hyomandibular and quadrate elements being fused with the cranium. The skull in such case is said to be autostylic, that is, with self-attached mandible. In the shark it is said to be hyostylic, the hyomandibular intervening. The upper jaw in the shark consists not of maxillary and premaxillary but of palatine elements, and the two h

n of Heterodontus ph

f Heptranchias indicus

alled mesopterygium, propterygium, and metapterygium, the first named being in the middle and more distinctly basal. These three segments are subject to much variation. Sometimes one of them is wanting; so

of a Flounder, Paralich

. In the Elasmobranchs the tail vertebr? are progressively smaller backward. If a caudal fin is present, the last vertebr? are directed upward (heterocercal) and the greater part of the fin is below the axis. In other forms (sting-rays) the tail degenerates

by a series of calcified rings. The palate with the suspensorium is coa

of a Toadfish, Batracho

f a Garfish, Tylosurus fod

Ganoids represent various phases of transition from th

has been called archipterygium by Gegenbaur, on the theory that it represents the condition shown on the first appearance of the pectoral fin. This theory i

dle of a Hake, Merluc

similar to the rays of the vertical fins. A muscle split into numerous fascicles extends all the length of the fin, which is flexible in every part and in every direction. The cartilaginous framework supporting it is joined to the scapular arch by a broad ba

. Kerr,[3] is probably without definite function, but belongs to the "category of modifications so often associated with the breeding season (cf. the newts' crest) commonly called ornamental, but which are perhaps more plausibly looked upon as expressions of the intense vita

TNO

. Trans.,