2700 THE LUNGFISHES AND CHIM^EROIDS 



jaw are molar-like, while there is also a small pair of cutting vomerine teeth in the 

 front of the upper jaw; the whole dentition thus closely corresponding to that of 

 the lungfishes, although there are two pairs of upper palatal teeth, which present 

 certain hardened areas known as tritors. The pectoral fins are shortened, without 

 the segmented axis of the lungfishes; and the first dorsal fin may have a movable 

 spine articulated to the spinous processes of the vertebrae. The sides of the body 

 show a lateral line; but there is no air bladder, and the nostrils do not open behind 

 into the cavity of the mouth. It has been suggested that the chimseroids indicate 

 a degenerate group nearly allied to the lungfishes, which have lost the membrane 

 bones of the latter, and acquired a superficial resemblance to sharks. 



The ugly fish, to which the name chimsera has been applied (Chimeera mons- 

 trosa), together with two other existing species, typically represents the family 

 Chimceridte, which alone has survived to the present day. The family is character- 

 ized by the presence of a spine to the first dorsal fin, and also of a prehensile. spine- 

 like structure on the heads of the males; there are no superficial plates on the skull, 

 and only a single pair of lower teeth. The family, which contains a number of ex- 

 tinct genera, mainly distinguished from one another by the characteristics of the 

 triturating areas on the teeth, dates from the Lias; the typical genus being, how- 

 ever, unknown before the latter part of the Tertiary period. The living chimseras 

 do not probably exceed five feet in length, and have the soft muzzle devoid of an 

 appendage. The dorsal fins occupy the greater part of the back; and the longitudi- 

 nal axis of the long filamentous tail is nearly continuous with that of the back, its 

 extremity being provided above and below with a long, low fin of the diphycercal 

 type. The common species represented in the annexed colored plate ranges from 

 Europe and Japan to South Africa; while a second occurs on the Pacific coast of 

 North America, and a third off Portugal. The southern chimasra (Callorhynchus 

 antarcticus) from the southern temperate seas differs from the preceding genus by 

 the presence of a cartilaginous prominence, ending in a flap of skin, on the muzzle, 

 and likewise by the upward direction of the extremity of the tail, which has no fin 

 on its upper surface. A fossil representative of this genus occurs in the Cretaceous 

 rocks of New Zealand. The third genus, Harottia, distinguished by the extreme 

 elongation of the snout, is represented by one species from the Atlantic, and a 

 second from the Pacific. As well-known extinct types of the family we may refer 

 to the Cretaceous and Tertiary genera Edaphodon and Elasmodus; the former includ- 

 ing fishes of gigantic dimensions. The members of the extinct family Myriacan- 

 thidtz, of the Jurassic rocks, differ by having a few bony plates on the head, and 

 three lower teeth; while the Squaloraiida ', as represented by Squaloraia of the Lias, 

 were somewhat ray-like forms, with a depressed trunk and elongated muzzle, and 

 no spines to the dorsal fins. The subclass appears also to be represented in Palaeozoic 

 times, the Devonian Ptydodus indicating a family which cannot at present be fully 

 defined. 



