50 FISH GALLERY. 



cases. An idea of the principal features of the bony framework of 

 a typical Fish may be given in the two accompanying engravings 

 of the skeleton of the Perch (fig. 37), as illustrative of the 

 Teleostean type, and of a Chondropterygian (fig. 42, p. 55), 

 Carcharodon rondeletii. 



Like that of the higher Vertebrates, the skeleton of a Fish 

 consists of the Skull (from which a branchial apparatus is sus- 

 pended), the Vertebral column, composed of vertebrae to which 

 ribs are attached, the Scapular arch, giving attachment to the fore 

 limbs (pectoral fins), and the Pelvic arch, giving attachment to the 

 hind limbs (ventral fins). Besides these parts, the typical Fish 

 possesses a series of dermal bones, spines, or rays, forming the 

 vertical fins, viz. dorsal, anal, and caudal. 



Looking at the Perch's skull from the side (fig. 37), we distin- 

 guish: The prcemaxillary (17), armed with teeth, and, parallel to 

 it, the toothless maxillary (18). The mandible (34), the right and 

 left rami of which are united by a ligament in front ; each ramus 

 is formed of three pieces, viz. the articulary (36), angular (35), 

 and dent.ary (34) bones, the latter armed with teeth. An infra- 

 orbital ring of bones (19), of which the anterior is the largest and 

 named pr&orbital. Four large bones, constituting the gill-cover, 

 and distinguished as prceoperculum (30), operculum (28), subuper- 

 culum (32), and inter operculum (33). 



The chain of flat bones which, after the removal of the tem- 

 poral muscles, appear arranged within the inner concavity of the 

 preoperculum, are comprised with the latter under the common 

 name of mandibulary suspensorium. They are : The epitympanic 

 (23), the mesotympanic (31), the pretympanic (27), and the 

 hypotympamc or quadrate (26), which has a condyle for the man- 

 dibulary joint. 



The palatine arch connects the suspensorium with the anterior 

 extremity of the skull and is formed by three bones the ento- 

 pterygoid (fig. 38, 25), the pterygoid (24), and the palatine (22) ; 

 the latter is toothed. 



In the occipital region (fig. 38) we have the basioccipital (o), 

 readily recognized by the conical excavation corresponding and 

 similar to that of the atlas, with which it is articulated through 

 the intervention of a capsule filled with a gelatinous substance (the 



