104 ANATOMY OF THE WOOD RAT 



of Homodontomys is much shorter and has a terminal en- 

 largement, upon which there are two lateral, curved ridges 

 and a medial one located more dorsad, these being arranged 

 petal- wise. In the central depression there is a long, 

 very slender, soft spine, through which passes the urethra. 

 In a single specimen trapped during early June, in which 

 the genitalia are in an active state, the penis is similar, 

 both in shape and size. In all three species first examined 

 of the three subgenera the prepuce extended from two to 

 five millimeters beyond the glans. 



In the distal tract of Neotoma there is embedded an os 

 penis 6.5 to 8 mm. in length. Distally this is spinous, 

 but its proximal end is broad and paddle-shaped (fig. 21C). 

 In Teonoma this bone is about 5.5 mm. in length, and in 

 Homodontomys it is apparently absent. It is likely, however, 

 that its size varies with age. 



In order to determine whether the form of the penis is 

 subgenerically or specifically uniform, an examination was 

 made of the penises of the three following forms, which 

 were the only ones of which adult males were available: 

 Neotoma intermedia from Riverside, California, taken in 

 late June when the genitalia had returned to quiescence. 

 The prepuce extended 18 mm. beyond the glans. In the 

 three species already discussed there were no discernible 

 preputial glands, but in intermedia there was a pair of 

 sacs nearly one millimeter in diameter and several in length 

 upon the dorsal side of the prepuce near its termination. 

 There was no well-defined gland in this area, but some of 

 the tissue is probably glandular in character, as indicated 

 by these sacs, which were filled with a white, cheesy matter 

 in the preserved specimen. The glans was 2.5 mm. in 

 diameter and simply cyUndrical, with the urethral orifice 

 slightly dorsad of the tip. The distal tract was 13, and 

 the proximal, 24 mm. in length. 



Neotoma micropus, from Fort Clark, Texas: date un- 



