700 REPORT OF NATIONAL MUSEUM, 1898/ 



ducts continue near or close together to the cloaca. The ovaries are 

 within elongate folds of the peritoneum. The oviduct is near the edge 

 of a deeper fold of the i^eritoneum on each side, and extends from near 

 the cephalic extremitj' of the ovary to a common cliamber or vagina, 

 which is above the rectum, and opens into the (;loaca. This vaginal 

 chamber is large, and is divided more or less completely in the Soleno- 

 glypli snakes, is about half divided or deeply bilobate in the Colu- 

 broidea, and is undivided in the Peropoda. Its external wall is deeply 

 longitudinally grooved, and the internal wall is transversely grooved in 

 Crotalus. In Colubroidea generally it is deeply longitudinally grooved 

 on all sides. In the Peropoda it is nearly or quite smooth. The cephalic 

 extremity of the oviduct is for a short distance transversely plicate or 

 lobate, the labia being held in place by simple unfolded bands of the 

 inferior and superior edges. The fontanelle is immediately cephalad of 

 this region, and has very thin simple walls. Being only a slit, it is 

 sometimes difficult to discover. The oviducts do not accompany the 

 ureters so closely as do the vasa deferentia, and approach nearer the 

 middle line for a short distance below the rectum. 



Like the Sauria the male Serpentes possess two intromittent organs 

 or hemipenes. Each is a cylindric hollow body, which when not in 

 use is retracted in a corresponding cavity on one side of the middle 

 line of the tail. Into its posterior extremity is inserted a cylindrical 

 muscle, which is continued posteriorly to a length generally greater 

 than that of the hemipenis, to an origin on a caudal vertebra. When 

 the hemipenis is in use it is protruded, and its inner surface is evag- 

 inated and becomes the external surface, the muscle just described 

 occuj^ying its center. It enters the vagina of the female and its 

 extremity occupies the corresponding anterior lobe of the latter when 

 present. It is withdrawn by the contraction of the central muscle or 

 retractor penis. The hemipenis is generally armed with reverted or 

 recurved spines. When this is the case the vaginal walls are very 

 tough. . When the hemipenis is unarmed the vaginal walls are thinner 

 and smoother. 



I have described the characters of the surface of the hemipenis in 

 1893,^ and have shown that they furnish good indications of affinity 

 and diversity among the snakes. The details then reported will be 

 found under the head of classification. The general characters may be 

 summarized as follows: 



The hemipenis of the Serpentes is traversed by a groove which 

 divides the external investment to the internal integument (or external 

 integument when the organ is retracted), which begins at the base 

 internally, and soon turns to the external side of the organ and con 

 tinues to its extremity. This is the sulcus spermaticus. This sulcus is 

 usually bifurcated in venomous snakes, and I find it to be equally bifur- 



' American Naturalist, XXIII, p. 477 ; Transactions of the American Philosophical 

 Society, XVIII, 1894, p. 186. 



