378 FISHES. 



upon its tail,) are composed of lobes, but are harder and more rounded, 

 being divided into very small lobules, and of a part softer and more 

 like the milt of other fishes ; in the squalus, the testicles are bulky 

 cylinders, bent as they wind, and divided at the inferior surface into 

 an infinite number of vessels : from the top of these bodies proceed 

 two epididymes, each composed of the infinite folds of one single 

 vas differens, which enlarges and is less twisted as it proceeds 

 towards the anus ; after being puffed into a kind of seminal ve- 

 sicule, it opens, with that of the other side, into a conical prominence 

 of the superior surface of the rectum near the anus, which may pass 

 for a penis, or at least serve for the same use during congress. 



The females of these same fishes have two ovaries, in which the 

 yolks of their eggs grow as in those of fowls; when they escape 

 they are seized by the two oviducts opening immediately above 

 the liver, and very near the diaphragm. These oviducts are mem- 

 branous and thin as far near as the middle of their length, where 

 each passes through a large kidney-shaped gland, formed of a peculiar 

 tissue, and which would seem to pour by means of thousands of pores 

 into the interior of the oviducts the substance proper for producing 

 the shell ; after having passed it, these canals descend and open at each 

 of the sides of a purse, situated behind or rather above the rectum, 

 and which forms a true womb : this purse is opened by a large 

 orifice at the extremity of the rectum, at its superior wall. 



When the rays and squalus wish to fecundate themselves, they bring 

 their bellies to each other, and the males have at their ventral fins 

 appendages often very complicated in their structure, and which appear 

 to enable them to seize with more power the tail of their females. 



The male sturgeon has its testicles suspended to the mesentery, and 

 is without a vas differens, but a tube rather large opens into the 

 abdomen, and receives there the semen, runs obliquely there towards 

 the base of the urethra, into which it terminates and empties itself, 

 as well as the urine, at an opening pierced behind the anus. 



The eggs of the rays are covered with a shell of a fibrous tissue, 

 resembling horn, enveloped externally and doubled internally by a 

 thick and glutinous membrane; its form is flattened, square, with 

 four angles prolonged into points. These eggs are commonly called 

 sea-bass or sea-mice* ; they contain besides a yolk, an albuminous 

 and transparent mass. The egg of the squalus is oblong, of homo- 

 geneous horn, often yellow and transparent : sometimes its surface is 

 elevated by transverse projecting laminse ; its angles are prolonged into 

 long, folded, and horny cords. 



It appears that this shell is formed when the egg passes the gland 

 which occupies the middle of the oviduct; it is formed by secretion 

 and by layers. When the egg is seized in the oviduct, it is sometimes 

 found still attached by its posterior part in the passage of the gland, 

 and this part is then soft and incomplete. I have reason to think 

 that the points of the egg in the rays and the cords of those of the 

 squalus, are drawn into the lateral furrows of that part of the oviduct 



* See Tilesius, on the eggs of horned fishes, and on the reproduction of the rays 

 and squalus (in German ; Leipsic, 1804, in 4to.) 



