CHARACTERS OF SOME HYSTRICOMORPH RODENTS. 



407 



truncated at the apex, and furnished witli a distinct lappet 

 beneath the genito-urinary orifice, between the labia of which it 

 projects as in Octodon and Ctenomys. The apex of the glans is 

 truncated, a little attenviated from the inferior aspect, but not at 

 all from the lateral view. The glandular pouch is moderately 

 deep, with laminate walls, two of the laminae extending from 



Text-figure 22. 



A. Tip of the glans penis of Octodon degtis, with glandular pouch cut open 



and the spikes turned to show the two prongs. In the normal position 

 one prong lies behind the other. 



B. Side view of anal and genital region of the same. 



C. Vertical section of anus of the same, showing median gland. 



D. Side view of anal and genital region of Ctenmm/s inendocinvs, 



E. Anus and penis, with glans protruded, of the same. 

 r. Side view of glans penis of the same. 



Lettering as in text-tig. 21. 



the tip of the glans being thick and ridge-like. There is no 

 trace of the hornv spikes seen in Octodon and Ctenomys. (Text- 

 fig. 21, A-C.) 



The prepuce of Octodon projects backwards a little way below 

 the anus. The penis is cylindrical with a conical apex, which is 

 smooth, the rest being closely covered with spicules. Between 

 the labia of the oi-ifice there is a small soft rounded process 

 underlying the genito-urinar}^ orifice. The pouch has corrugated 



