CLOACAL GLANDS OF MALE NECTURUS 449 



numerous transverse fissures and, immediately caudad to the 

 paired external papillae, there is a distinct transverse crescentic 

 groove. A ventral enlargement extending laterall}^ along the 

 cloacal slit and cranially toward the region of the pelvic girdle 

 marks the extent of the large cloacal gland. 



INTERNAL TOPOGRAPHY OF THE CLOACAL CAVITY 



For purposes of description, the cavity of the cloaca may be 

 considered as consisting of two portions, an enlarged caudal 

 chamber or vestibule opening ventrally to the exterior by way 

 of the cloacal slit and a narrower cephalic, tubular portion 

 connecting the cloacal chamber with the rectum (figs. 4, 5, 

 cl.ch., cl.t.). 



The internal configuration of the cloaca is decidedly complex, 

 but in an undistended condition the cavity exhibits a very defi- 

 nite and constant form. The various depressions, folds, papil- 

 lae, etc., which go to produce the complicated pattern of the 

 cavity serve therefore as landmarks of the different regions into 

 which the tubular glands discharge their secretion. 



Before entering upon the more detailed description of the 

 several regions of the cloaca, brief mention will be made of the 

 most conspicuous modifications of the cloacal wall. The ventral 

 side of the cloacal tube has the form of a deep, narrow trough, 

 the mucosa of which is thrown into high, 'thin ridges (figs. 4, 5, 

 12, 13, 14, v.tr., vs.). Caudally, in the region of the cloacal 

 chamber, the ventral ridges are interrupted and merge into tall, 

 slender papillae (figs. 4, 5, 15, int.pp.). Dorsally the cloacal 

 tube contains a deep median groove (figs. 4, 5, 13, 14, 7nd.gr.) 

 and on its sides between the dorsal groove and the ventral 

 trough are two well-defined longitudinal furrows (fig. 13, It.fur.). 



The cephalic end of the cloacal tube presents the simplest 

 condition, and the transition from rectum to cloaca occurs with- 

 out any very evident change in structure. The urogenital 

 ducts open dorsolaterally into the extreme cephalic end of the 

 tube. They terminate separately in a pair of prominent papil- 

 lae which project ventrally from the bottoms of two pit-like 

 depressions (figs. 4, 5, 7, ug.p.). The urinary bladder opens 



