CLASS PISCES. 505 



.) 



Their palatine and post-mandibular bones, alone 

 armed with teeth, serve instead of jaws, and the 

 ordinary bones of the jaws only exist in a rudimentary 

 state ; a single bone suspends these apparent jaws to 

 the cranium, and represents at once the tympanic, 

 jugal, and temporal bones, and the preoperculum. 

 The os hyo'ides is attached to this singular pedicle 

 of which we have just spoken, and bears branchioste- 

 gous rays as in ordinary fishes, although they do not 

 appear so much externally. It is even followed by 

 branchial arches, but there are none of the three 

 pieces which compose the operculum. These fishes 

 have pectorals and ventrals ; the latter are situated 

 behind the abdomen, and on the two sides of the 

 anus. Their membranous labyrinth is enclosed in 

 the cartilaginous substance of the cranium ; the sac, 

 which forms a part of it, contains only amylaceous 

 masses, and not stones. The pancreas is in the form 

 of a conglomerate gland, and not divided into tubes 

 or distinct cceca. The intestinal canal is short in pro- 

 portion, but a part of the intestine is furnished in- 

 ternally with a spiral lamina, which prolongs the 

 stay of the aliments. 



In sexual intercourse there is a real intromission ; 

 the females have oviducts very well organized, which 

 serve in lieu of matrix to those whose young are dis- 

 closed in the body ; the others form eggs, invested 

 with a hard and corneous shell, to the production of 

 which, a thick gland which surrounds each oviduct 

 contributes. The males are recognized by certain 



Qq2 



