res which are to be readily seen without dissection, we are prepared to examine its anatomy in d

. They are longer than broad or deep and the greatest width is in front of the

Monocentris japonicus

but on the thorny skin or a bony coat of mail. Some of these are almost globular in form, and their outline be

, Diodon hystrix (Linn

hthys avocetta Jordan and

Hippocampus hudsoni

sh, Peprilus paru (

ushima Bay, Japan. (The short line in all cases shows the deg

pines to its bony box, and the porcupine fish (Diodon hystri

e protected by a leathery skin. Other fishes, as the eels, are extremely long and slender, and some carry this elongation to great extremes. Usually the head is in a line with the axis of the body, but in some cases, as the sea-horse (Hippocampus), th

s the Peprilus (Fig. 10) is said to be compressed, while the fishing-frog (Lophius) (Fig. 11) has a depressed body and head. Other

length. The usual standard of measurement is the length from the tip of the snout to the base of the caudal fin. With this length the greatest depth of the body, the greatest length of the head, and the

ng fishes have the eye larger, the body slenderer, and the head larger in proportion than old fishes of the same kind. The mouth grows larger with age, and is sometimes larger also in the male sex. The development of the fins often var

the West Indies, Epinephelus adsce

e exoskeleton, whatever form it may assume, may be held to consist of modified scales, and this is usually obviously the case. The skin of the fish may be thick or thin, bony, horny, leathery, or papery, or it may have almost any intermediate character. When pro

adly classified as ctenoid, cycl

cloid. Ctenoid scales have a comb-edge of fine prickles or cilia; cycloid scales have the edges smooth. These two types are not very different, and the one readily passes into the other, both being sometimes seen on different parts of the same fish. In general, however, the more primitive representatives of the typical fishes, those with abdominal ventrals an

times soft and scarcely noticeable, when they are known as ciliate or eyelash-like. Such scales are possessed in general

anthoessus bronni (Ag

h are evidently modifications of these primitive structures. Some other fishes have scales which appear shagreen-like to sight and feeling, but only the sharks have the peculiar structure to wh

red with bony enamel, much like that seen in teeth, otherwise essentially like cycloid scales. These are found in the garpike and in many genera of extinct Ganoid and Crossopterygian fishes. In the line of descent the placoid scale preceded t

.-Cyclo

Some are scaly everywhere on head, body, and fins. Others may have only a few lines or patches. The scales may be everywhere alike, or they may in one part or another be greatly

shes it follows rather the outline of the belly. It is subject to many variations. In some large groups (Gobiid?, P?ciliid?) its surface structures are entirely wanting. In scaleless fishes the mucous tube lies in the skin itself. In some groups the lateral line has a peculiar position, as in the flying-fishes, where it forms a raised ridge bounding the belly. In many cases the lateral line ha

of channels in or under the skin. These channels are filled with mucus, which exudes through occasional open pores. In many fishes the bones of the skull are cave

teral lines), Porichthys porosissim

ood. As the structures of the lateral line are well provided with nerves, it has been thought to be an organ of sense o

and in its later differentiation acquired its metameral characters." In view of its peculiar nerve-supply, "the precise function of this entire system of organs becomes especially difficult to determine. Feeling, in its broadest sense, has safely been admitted as its possible use. Its close genetic relationship to the hearing organ suggests the kindred

fins below or behind them represent the hinder limbs. Either or both pairs may be absent, but the ventrals are much more frequently abortive than the pectorals. The insertion of the ventral fins may be abdominal, as in the sharks and the more generalized of the bony fishes, thoracic under the breast (the pelvis attached to the shoulder-g

he lower median line the anal fin. The dorsal is often divided into two fins or even three. The anal is

rays are also sometimes articulate. Rays thus jointed are known as soft rays, while those rays which are neither jointed nor branched are called spines. A spine is usually stiff

e such rudiments in front of their vertical fins. The pectoral, as a rule, is without spines, although in the catfishes and some others a single large spine may be developed. The ventrals when abdominal are usually without spines. When thoracic each usually, but not always, consists of one spine and five soft rays. When jugular the number of soft rays may be reduced, this being a phase of degeneration of the fin. In writing descriptions of fishes the number of spines may

ns lie along the sides of the body, forming the flesh of the fish. They are li

eat lateral muscle, composed of flake-like segments (myocommas) which correspond in general with the number of the vertebr?. In general the muscles of the fish are white in color.

e modified into electric organs. These

TNO

ecent and Fo