CHARACTERS OF SCAllTUKUS AKD OTHER JERBOAS. 677 



above, and its glans is slender and subcylindrical, according to 

 Tullberg *. 



In all the specimens of Jaculidse examined the anal and gene- 

 rative orifices are so closely applied that on superficial inspection 

 there appears to be a single orifice only, situated upon, a thick 

 naked excrescence a little distance below the root of the tail. 

 In the females, indeed, the vulva and anus are slightly insunk, 

 and are closed by a common sphincter. In the males the tip of 

 the penis in its natural position is pressed up against the lower 

 side of the anal prominence which carries the anal orifice, con- 

 cealed from view, on its underside. This prominence is exceed- 

 ingly large in Scirtopoda oj-ientalis (text-fig. 36, A, B). 



The penis of Scirtopoda orientalis was first described by Sonninit 

 and Olivier t. The glans is large and oval in shape, and is thickly 

 covered with many backwardly directed short spines ; but, in 

 addition, it is armed vvdth a pair of long slender stiliform spikes, 

 like those in the pouch of the glans of Ccelogenys, Cavia, and 

 some other Hystricomorphs. These spikes are rigid, excejat at 

 the tips, which are soft. According to Sonnini, these tips form 

 a small yellow button like the anthers of certain flowers ; but 

 in the specimens examined by me they were pointed and only 

 distinguishable by their softness from the rest of the spike. 

 Normally these spikes lie forwards upon what is the upper side 

 of the penis when this organ is extended from the prepuce and 

 directed forwards, and their tips overlap the apex of the glans ; 

 but they are capable of being elevated or even directed back- 

 wards. Beneath the narrowed apex of the glans the large orifice, 

 which has an upper and a lower lip, opens, and on each side of 

 it there is a shallow, probably glandular, pouch. The lower side 

 of the glans is provided with a median, probably glandular, 

 gutter, the edges of Avhich, when brought together, form a 

 narrow lineal crease (text-fig. 36, C-F). In Jacidus jaculus the 

 glans penis is very diflferent, as Anderson and de Winton pointed 

 out. It has no spikes, and the small spines seen in Scirtojyoda 

 orientalis are represented by minute pits, in each of which there 

 is sunk a scale with serrulate free edge. There is a median 

 thickening on what is the upper side of the penis when this 

 organ is turned forwards, and there is a narrow median groove 

 below. There is a curved groove above the upper lip of the orifice 

 and a small prominence on each side of it, but no glandular 

 depression. (Text-fig. 36, G-I.) 



In Scarturus the glans is oval or cordate from above or below, 

 pointed from the side-view, and the tenninal orifice is simple. 

 It is armed with sharp recvirved spines, which are fewer in number 

 and relatively larger than in Scirtopoda orientalis, but there is 



* In tlie specimen I examined the tip of the glans was covered with an extra- 

 neous thickening of hard material closely adherent to it. 

 t Voy. en Ea-vpte, i. pp. 173-174 (1800). 

 I Bull. Soc. Phil. Paris, ii. no. 40, p. 121 (1801). 



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