320 



REPTILIA. 



of the penis a canal which at one extremity 

 communicates with the cavity of the peri- 



Fig. 238. 



Section of the Penis of the Tortoise to show its 

 internal Structure. (After Bojanus.) 



10, tendinous floor of urethral groove ; 55', ten- 

 dinous insertions of the retractor muscles of the 

 penis ; f, tendinous walls of the urethral groove 

 enclosing the peritoneal canals ; e, lateral cavernous 

 substance of the penis ; 4, median cavernous sub- 

 stance separated from the preceding by the tendinous 

 septum 9 ; 5, urethral groove bounded on each side 

 by the cavernous bodies. 



toneum on each side of the bladder, and by 

 its other end it is prolonged into the substance 

 of the penis as far as the glans, where it ter- 

 minates in a cul-de-sac, without being per- 

 forated by any orifice throughout its whole 

 extent. 



The penis of the Chelonians is furnished 

 with two retractor muscles (fig. 239. 55), 

 which arise from the pelvis, and are prolonged 

 as far as the under surface of the glans ; these 

 fold up the organ into the cloaca in such a 

 manner that it closes up the orifice of the 

 rectum, and also that of the urinary bladder, as 

 in the ostrich. 



Erection is doubtless produced by the 

 action of the sphincter muscle of the cloaca. 



In Crocodiles the penis is likewise single, 

 and not enclosed in a sheath like that of other 

 Saurians and of Ophidians. This penis is 

 conical in shape, and is grooved along the 

 whole length of its dorsal region by a deep 

 urethral furrow : it is principally composed of 

 a fibrous and elastic corpus cavernosum, the 

 texture of which is very firm. That portion 

 which represents the glans is softer than the 

 rest, being composed of vascular and erectile 

 tissue : it advances above the apex of the 

 corpus cavernosum, and is prolonged beyond 

 it, so that there are two points thus formed, 

 one situated above the other ; these points 

 are united together on each side, and also in 

 the middle by a vertical septum which di- 

 vides the interspace between them into two 

 culs-de-sac. The urethral groove is con- 

 tinued as far as the extremity of the upper 

 point. 



The substance of this penis is, generally 

 speaking, solid, and composed of a very 

 dense fibrous substance, without any inter- 

 mixture of erectile tissue ; in this respect the 

 penis of the crocodile resembles that of the 



ostrich. There is no erectile tissue discernible 

 except at the root of the corpora cavernosa, 



Fig. 239. 



K 



The Penis of the Tortoise. 



A B, the rectum ; c, vas deferens ; F, terminations 

 of the vasa deferentia, in the commencement of o, 

 the urethral groove ; H, corpus cavernosum ; i, the 

 glans penis ; K, end of urethral groove ; 55', re- 

 tractor muscle of the penis. 



from which part it is continued along the 

 sides of the urethral fissure as far as the glans, 

 the substance of which it principally forms. 



The peritoneal canals, which exist in the 

 crocodiles as well as in the Chelonian reptiles, 

 do not in the former enter into the com- 

 position of the penis, as they do in the latter ; 

 they merely pass along the base of the penis 

 to open into the cloaca by a wide orifice : 

 neither have they in their course any com- 

 munication with the body of the penis ; an 

 arrangement very different from that described 

 above as existing in the tortoises, where they 

 terminate in a cul-de-sac in the substance of 

 that organ. 



In the other Saurians the penis is either 

 doubled or bifurcated, each portion consisting 

 of a conical or cylindrical portion which forms 

 a sheath that during erection becomes unrolled 

 like the finger of a glove, in such a manner 

 that what before constituted a cul-de-sac 

 becomes, when developed, the extremity of 

 the penis. When thus developed, the two 

 penises protrude from the two lateral com- 

 missures of the lips which bound the trans- 

 verse opening of the cloaca ; when thus pro- 

 truded, they are generally found to be studded 



