318 



REPTILIA. 



and conforms very closely to what exists in 

 the class of birds. The testicles are invariably 

 two in number, and situated in the abdominal 

 cavity on each side of the spine, their po- 

 sition being more or less advanced forwards 

 according to circumstances : they are, how- 

 ever, constantly in juxtaposition with the 

 kidneys, beneath or in front of which they are 

 always placed. In the Chelonians they are 

 always found to be connected with the in- 

 ferior surface of the renal glands, which are 

 here situated at the bottom of the abdominal 

 cavity. In the Saurians they are placed in 

 front of the kidneys on each side of the spinal 

 column. They occupy a similar position in 

 the Ophidian order, except that the right 

 testis is in all serpents advanced further 

 forwards than the left. 



The intimate structure of the testis is es- 

 sentially similar in all the reptilia. Each testis 



Fig. 234. 



Male Organs of Generation, and Kidney of the 



Tortoise. {After Bojanus.} 



M, M", the urinary bladder laid open ; o, the left 

 kidney ; p, the renal capsule ; 8, uriniferous tubes 

 derived from the kidney, which by their union form 

 the ureter ; N, ureter ; F, common termination of the 

 ureter and of the vas deferens at the neck of the blad- 

 der, close to the commencement of the urethral 

 groove; M, ditto of the opposite side; y, the 

 testes ; c, the vas deferens ; E, the bulb of the 

 penis ; G, commencement of the urethral groove, just 

 anterior to the openings common to the ureters and 

 the vasa deferentia. 



is found to consist of large fascicles of semi- 

 niferous tubes, which are connected together 

 by a delicate cellular tissue, and are, generally, 

 easily separable. The seminal ducts derived 

 from all these fascicles unite to form the com- 

 mencement of the vas deferens, which is very 

 tortuous and folded upon itself, so as to form 

 an epididymus situated at the side of the 

 testis. In the Chelonian reptiles the con- 

 voluted mass of tube which forms the epididy- 

 mus is continuous with a very flexuous vas 

 deferens, which is continued as far as the 

 cloaca, into which it opens close to the root 

 of the penis, and in the immediate vicinity of 

 the grooved canal, which, in these animals, 

 represents the urethra. 



In Saurians the epididymus forms a detached 

 mass of a pyramidal form, which is longer 

 than the testis itself. The vas deferens de- 

 rived from it, runs along the external border of 



the kidney as far as the cloaca, into which it 

 opens. 



In Ophidian reptiles the epididymus is 

 proportionally of smaller size, and is in like 

 manner continuous with a flexuous vas de- 

 ferens, which terminates in the cloaca. 



The terminal orifices of the vasa deferentia 

 are always situated in the upper wall of the 

 cloaca, external to or above the ureters, and 



Hinder Part of the abdominal Cavity of Draco volans. 

 a a, depressor muscles of false ribs ; b, testes ; c, 

 vas deferens ; d, bladder ; e, rectum. 



are disposed in such a manner, that when the 

 penis is double, the orifice of each vas de- 

 ferens is close to the commencement of the 

 urethral groove of the corresponding penis 

 when in a state of erection. When the penis 

 is single, both the orifices of the vasa de- 

 ferentia open in the vicinity of the single 

 urethral canal. In some Ophidians the vasa de- 

 ferentia, near their termination in the cloaca, 

 dilate into a kind of ampulla, which seems to 

 be a reservoir for the reception of the seminal 

 fluid. 



The cloaca in the reptilia is a wide cavity 

 which receives the terminations of the rectum, 

 of the ureters, of the allantoid bladder, when 

 that viscus is present, and likewise of the vasa 

 deferentia. In the Chelonians and in the 

 crocodiles, which have a single penis, that 

 organ, when in a state of repose, is entirely 

 concealed in the cloacal cavity, the external 

 opening of which is in these genera an oval 

 or longitudinal opening. In the Chelonians 

 the cavity of the cloaca may be divided into 

 two portions : the one anterior, which is of a 

 cylindrical shape, and receives the termination 

 of the rectum, has its mucous membrane 

 gathered into numerous longitudinal folds, and 

 is surrounded with two layers of muscular 

 fasciculi ; the external assuming a longitu- 

 dinal, and the internal a circular arrangement. 



