COLD-BLOODED VERTEBRATES 



1043 



inp;, although he admits that he never oh- 

 served this iirocess. Siniihir structures have 

 l)ecn described on the medial surfaces of 

 the hind limbs of Diemectiihis^ iTriturus) 

 (Jordan, 1891). 



A dorsal crest or skin fold is connnon on 

 adult male urodeles during the breeding 

 season. The crest usually extends along the 

 back and tail and in profile makes the ani- 

 mal look much larger. Special masculine 

 skin {)igmentation may occur. Secretions 

 from hedonic glands on the chin and ad- 

 jacent areas in Eurycea and Tritnrus per- 

 \vdps attract females; these glands begin to 

 accumulate their product in November and 

 are distended by the start of the breeding 

 season in March. Cloacal glands are a dis- 

 tinctive male characteristic of Desmogna- 

 thus, Triturus, and other salamanders. Sea- 

 sonally, the epithelial cells of these glands 

 become tall and accumulate granules. Pos- 

 sibly the glandular secretion of Desmogna- 

 thus may form the spermatophores.^- 



The male D. fuscus has a monocuspid 

 premaxillary tooth which differs from that 

 of the female (Noble, 1926). 



The linea masculina is a curious and dis- 

 tinctive band of connective tissue lying at 

 the dorsal and ventral edges of the obliquus 

 abdominis muscles in various adult male 

 ranid frogs, but not in toads (Liu, 1935; 

 Davis and Law, 1935; Schmidt, 1938). Fore 

 limb muscles (fiexor carpi radialis, extensor 

 carpi radialis, abductor pollicis longus) are 

 much larger in adult male than in female 

 toads such as Bufo a. ainericaniis, ap- 

 parently aiding the powerful and prolonged 

 grasping of the female during amplexus. 

 As Howell (1935), who described this in- 

 teresting specialization, has remarked, it 

 would be desirable to study the effects of 

 gonadectomy and gonad transplant on these 

 muscles. 



Reptiles 



The lizard's cloaca shows sexual speciali- 

 zation. It is divided into an anterior cop- 

 rodeum, receiving the small intestine, an 

 intermediate urodeum, and a posterior proc- 

 todeum. Adjoining chambers are separated 



^-Jordan, 1891; Biesca, 1910; Anm, 1924b: 

 Humphrey, 1925; Noble, 1926, 1931; Adams, 1940; 

 Weiflioit, 1945. * 



l)y sphincter muscles. From the urodeum 

 arises a dorsal urogenital diverticulum of 

 varying size ; into this diverticulum or fossa 

 usually open conjointly the ureter and vas 

 deferens in the male and, separately, the 

 ureter and oviduct in the female (Gadow, 

 1887; Regamey, 1935; Forbes, 1941). 



In the male Lacerta agilis (Regamey, 

 1933, 1935) the urogenital diverticulum, 

 urodeum, and anterior proctodeum are lined 

 in the spring with tall, columnar, stratified 

 ( two or three layers ) epithelium containing 

 many mucous cells. The total depth of the 

 epithelium is 35 /x. In June and July, dur- 

 ing the breeding season, the epithelium 

 thickens to 40 to 45 ju,. The urodeum, an- 

 terior proctodeum, and terminal portion of 

 vas deferens (a urogenital fossa is lacking) 

 of the adult male Sceloporus spinosus flori- 

 darnis has a bilaminar epithelium (Forbes, 

 1941). Its inner stratum is formed of a 

 single layer of columnar cells. Peripheral to 

 them is a second layer, in most areas one 

 cell thick, of cuboidal and low columnar 

 cells. The regularly arranged nuclei of the 

 two layers present a striking appearance. 



Opening into the anal vestibule, or ter- 

 minal portion of the proctodeum, in male 

 Lacerta and Sceloporus are cloacal glands. 

 One pair lies anterior and ventral, the others 

 (a single gland in Lacerta, a pair in Scelop- 

 orus) lie i)osterior and dorsal, to the proc- 

 todeum. The glands lack definitive capsules 

 and consist of numerous lobules separated 

 by thin but dense connective tissue septa. 

 Each lobule forms an acinus-like epithelial 

 pouch, sometimes containing a little secre- 

 tion. 



Several lizard genera have femoral glands 

 which are developed as male accessory sex 

 structures.^-^ In Lacerta there are 16 to 21 

 glands on the anterior surface of each thigh. 

 The glands lie just under the skin and open 

 by way of a short duct which penetrates a 

 conical elevation of the skin. The duct open- 

 ings are visible macroscopically. The golden- 

 yellow secretion of the glands is abundant 

 dui'ing the bi'eeding season.'^ 



"von Leydig, 1872; Braim, 1877; Schaefer, 1901, 

 1902; Cohn, 1904; Tolg, 1905; Mahendra, 1936, 

 1953; Forbes, 1941. 



''Felizet, 1911; Reiss, 1923b; Matthev, 1929; 

 Suchow. 1929; Padoa, 1933; Regamey, 1935. 



