HEPTILIA. 



319 



This portion of the cloaca is bounded both 

 before and behind by a ring projecting in- 

 ternally, composed of strong muscular fibres, 

 which form two sphincter muscles. 



The second portion of the cloaca has its 

 walls thinner than the preceding. The longi- 

 tudinal folds of the mucous membrane of the 

 first portion suddenly terminate, with the 

 exception of the median fold, which is con- 

 tinued around the termination of the ureter, 

 enclosing it, as it were, between two broad 

 lips, which are then prolonged in the shape of 

 two folds along the median line of the dorsum 

 of the penis, becoming gradually less distinct 

 as the urethral groove which they bound 

 becomes deeper : it is in this second portion of 

 the cloaca that the penis is folded up when in 

 a state of repose. 



In the crocodiles the disposition of the 

 cloaca is nearly similar, but in these Saurians 

 there exist on each side of the root of the 

 penis two wide apertures, through which a 

 free communication is established between 

 the exterior and the cavity of the peritoneum. 



In the caiman (Alligator sc/crops) the cloaca 

 is divided into three compartments, the ante- 

 rior of which receives the rectum ; the second 

 contains the orifices of the vasa deferentia, of 

 the ureters, and of the allantoid bladder; 

 whilst the third is appropriated to the lodgment 

 of the penis. In this case the dorsal groove 

 of the penis is bounded by two folds of mu- 

 cous membrane, which are prolonged back- 

 wards into the middle chamber, so as to 

 establish a communication with the openings 

 of the vasa deferentia. 



In those reptiles which have the penis 

 doubled, viz. the Saurians (minus the croco- 

 diles) and the Ophidians, these organs are 

 not enclosed in the cloaca : in such races the 

 external opening of the cloaca is always a 

 transverse slit, bounded by two lips, the pos- 

 terior of which is more or less moveable : it is 

 between these lips, just within their lateral 

 commissures, that the two male organs are 

 situated. 



The posterior lip of the cloaca encloses in 

 its substance a series of orifices which are the 

 openings of the excretory ducts of as many 

 little glands, which seem to represent the 

 anal glands of other vertebrata : they secrete 

 a thick sebaceous matter. 



Besides these, there are in many genera of 

 reptiles a series of crural glands, situated near 

 the orifice of the cloaca ; these exist in all the 

 Lacertidas. In many Iguanidae and other 

 Saurians these glands become largely deve- 

 loped as the season for impregnation ap- 

 proaches. 



In the Chelonian reptiles the penis is very 

 large, and both in its structure and form 

 somewhat resembles that of the ostrich. It 

 is long, nearly cylindrical in its shape, and 

 enlarged towards its extremity, which termi- 

 nates in a point. A deep groove extends 

 along the whole length of its dorsal surface, 

 which becomes gradually deeper as it ap- 

 proaches the glans, near the middle of which 

 it terminates by a kind of orifice, divided into 



two by a papilla. From the depth of this 

 groove it is evident that the mere approxi- 



Fig. 236. 



Penis of the Tortoise. (After Boj anus.) 

 E, bulb ; L, corpus cavernosum ; H, urethral 

 groove; K, its termination near the centre of the 

 glans ; i, glans penis ; 55', retractor muscle. 



mation of its edges will convert it into a 

 complete canal. 



This penis is composed of two corpora 

 cavernosa, the fibrous walls of which are 

 blended together throughout some part of 

 their extent. They commence by two vascular 

 enlargements, analagous to the bulb of the 

 urethra in the penis of mammalia. The erectile 

 tissue is prolonged from this bulb (fg. 236), 



Fig. 237. 



Male Organs of Generation of the Tortoise. (After 



Bojanus.) 



a, the rectum ; c, convolutions of epididymus 

 terminating in the vas deferens ; N, which likewise 

 indicates the point where the urethra enters the 

 cloaca ; o, p, the kidney ; y, the testes ; E, the bulb 

 of the urethra ; K, cavernous portion ; M, the urinary 

 bladder ; Q, the left supernumerary lateral bladder ; 

 Z, r, r', s, x, z, blood-vessels ; 55, retractor muscle 

 of the penis. 



along two canals, the walls of which are 

 fibrous, and at first very thin ; but they soon 

 increase in thickness considerably, their cavity 

 becoming diminished in the same proportion. 

 All the enlargement that constitutes glans is 

 composed of this vascular tissue, prolonged 

 from the cavernous body, which is covered by 

 a loose and wrinkled skin, and, moreover, sup- 

 ported by a prolongation of the fibrous wall 

 of the corpus cavernosum, which is continued 

 to its point. 



The skin which lines the urethral groove 

 has also a layer of this erectile tissue placed 

 beneath it ; but this is equally a prolongation 

 from the erectile tissue contained in the ca- 

 vernous body. 



There is on each side of the dorsal groove 



