962 



PISCES. 



In the Cyprinid/e this bone is of very rudi- 

 mentary size, and is totally wanting in the 

 Muranidtf, the Anarrhicus, and the Siluridte. 



The carpal bones, which support all the rays 

 of the pectoral fin except the first, are gene- 

 rally placed, as above described, in a single 

 row consisting of four or five pieces, but occa- 

 sionally each of these bones presents a con- 

 striction near its middle, so as to have the 

 appearance of being divided into two. 



It is the bones of the carpus, and not 

 those of the arm or fore-arm, which are elon- 

 gated to give the pediculated structure to the 

 feet of the frog-fishes, making them look like 

 arms. In Lophius these are only two in num- 

 ber; in Polypterus there are three, and in 

 Batrachus five. In these Fishes the radius 

 and ulna are reduced to a very small size. 



Posterior extremity. The os innominatum, 

 the femur, the bones of the leg and of the tarsus, 

 are all represented in the osseous Fishes by a 

 single bone (jig. 493, 12) of a triangular shape, 

 and presenting several processes and prominent 

 lamellae. The apex of this triangle is directed 

 forwards, and in the subrachial Fishes is attached 

 in the angle formed by the junction of the two 

 ossa humeri (11), at the point where the latter 

 bones are united to each other by symphysis 

 beneath the throat. In the true abdominal 

 Fishes the pelvic apparatus is unattached to 

 any part of the skeleton, being simply imbedded 

 in the muscles beneath the belly. 



The posterior extremity of the piece last men- 

 tioned gives attachment to the rays of the ventral 

 fin (13), at the inner margin of which it not 

 unfrequently gives off a long process extending 

 backwards. The two pelvic pieces of the op- 

 posite sides are most frequently united to each 

 other by a suture; but it sometimes happens 

 that they remain partially separated either to- 

 wards their anterior part, as in Lophius, or pos- 

 teriorly, as in Batrachus. 



Many Fishes, as Murana, Gymnotus, Xi- 

 phias, &c. have no ventral fins, and in such 

 cases the pelvic apparatus is altogether wanting. 



Fin rays of the. extremities. These rays, 

 with the exception of the most external one 

 belonging to the ventral fin, are all soft and 

 composed of numerous articulations, but to- 

 wards their base they are more compact than 

 elsewhere, the articulations being there scarcely 

 visible. The base of each ray is enlarged so as 

 to permit of its being firmly attached to the 

 radial bone and to those of the carpus and 

 pelvis. 



The first ray of the pectoral fin is rarely 

 branched, and its articulations are sometimes 

 so completely consolidated as to simulate a 

 spinous ray. This is the case, for instance, in 

 Stlurus among many other Fishes ; but in such 

 cases they are not really spinous rays in spite of 

 their near resemblance, but derivations from the 

 dermal skeleton, so that such Fishes are in all 

 respects strictly malacopterygious. 



Verticuljins. The vertical fins of the osseous 

 Fishes, namely, the dorsal, the caudal, and the 

 anal fins, cannot be compared to any portions of 

 the skeletons met with in other Verlebrata. 

 They belong, in fact, to the exoskeleton (see 



OSSEOUS SYSTEM), but are so intimately re- 

 lated to the real bones both in structure and 

 office, that they must be described in this 

 place as being essentially connected with the 

 bony framework of the body. 



Every one of the vertical rays entering into 

 the composition of these fins consists of two 

 portions, an interspinous bone, which is im- 

 bedded in the flesh of the fish between the 

 great lateral muscles, and serves as a basis to 

 which the ray is attached, and the ray itself, 

 which is visible externally and generally assists 

 in supporting the membrane of the fin. 



Interapinous bones- The interspinous bones 

 form a series reaching along the back to an ex- 

 tent proportioned to the length of the dorsal 

 fin, and in a similar manner are appended be- 

 neath the post-abdominal region of the ventral 

 surf-ice coextensively with the anal fin, which 

 they resemble. Each interspinous bone (fg. 493, 

 3, 3, 6, 6) resembles in its shape the blade of a 

 dagger plunged into the flesh, while its head cor- 

 responding with the handle of the dagger remains 

 on a level with the skin to give attachment to 

 the base of the ray. This portion of the inter- 

 spinous bone has an apophysis conjoined with 

 it by suture, which in many instances is pro- 

 longed into a point that is connected to the 

 articulation of the next ray of the fin. The 

 interspinous bones are generally so disposed 

 that their points penetrate between the spinous 

 processes of the vertebrae, each being attached 

 to these processes by a ligamentous membrane ; 

 but there are some Fishes, as the Pleuronectidg 

 (fig. 493), and (as regards the composition of 

 the anal fin) the Siluri, in which there are two 

 interspinous bones to each spinous process, and 

 in other cases the relations between the two be- 

 come quite lost, as, for example, where three or 

 even four spinous processes are interposed be- 

 tween some of the vertebral spines, a fact which 

 in itself is sufficient to disprove the hypothesis of 

 GeofTroy, extensively promulgated in this coun- 

 try by the writings of Professor Grant, namely, 

 that the interspinous bones of Fishes are dis- 

 memberments of the spinous processes, one- 

 half of the latter becoming displaced and forming 

 the interspinous bone as well as the ray which it 

 supports. 



On this point Cuvier remarks that in many 

 genera, such as Mursena, Ophicephalus, and 

 Gymnotus, the inferior interspinous bones are 

 separated from the vertebrae by the cavity of 

 the abdomen, which is prolonged to a consi- 

 derable distance beyond the commencement of 

 the anal fin ; whilst in other cases, as in the 

 Pleuronectidae, there are interspinous bones 

 even upon the cranium (fig. 493,1). These cir- 

 cumstances, joined to the fact that in those por- 

 tions of the back or of the tail which have no fins 

 attached to them there are generally no interspi- 

 nous processes although there are vertebral spines, 

 make it impossible to regard the bones in 

 question as being derivations from the vertebral 

 column. 



Rays of the vertical fins. Each fin-ray (jig. 

 493, 2, 7 j is connected with its corresponding 

 interspinous bone by a ginglymoid articulation. 

 The rays are of two kinds : spinous rays, such as 



