UROGENITAL SYSTEM 105 



known but sexually active, with seminal vesicles enlarged. 

 The prepuce was devoid of glandular sacs and extended 

 5 mm. bej^ond the glans. The latter was much swollen, 

 with a diameter of 7 mm., cylindrical and with an internal 

 opening 2 mm. in diameter, this enlarging with the glans 

 to an internal diameter of more than 3 mm. This was 

 filled with a transparent, jelly-like substance, and cen- 

 trally within it was the spinous os penis, terminating, within 

 the glans, in an acute, soft spine. The distal tract was 20, 

 and the proximal 22 mm. in length. 



Neotoma floridana rubida, from New Orleans, Louisiana, 

 July: sexually active, with seminal vesicles enlarged. The 

 penis was of the same general type as the last, but was less 

 extreme in development. 



The conclusions reached from the examination of this 

 material is that the forms rubida, micropus and albigula of 

 the subgenus Neotoma have penises of the same general tj^pe 

 while those of Neotoma intermedia, Homodontomys, and 

 Teonoma are all different to an important degree. The 

 precise effect of sexual activity or inactivity upon the shape 

 of the glans can not be ascertained without a large series 

 illustrating all stages of seasonal variation in this respect. 

 It seems certain, however, that the glans penis will be found, 

 when sufficient material is available, to constitute a very 

 valuable character for ascertaining group relationships. 



In the sexually inactive specimens the more distal por- 

 tion of the corpora cavernosa could not be well defined, 

 as they were shrunken, pale, and without detail. In Neo- 

 toma they were swollen, engorged with blood and very dis- 

 tinct. In all specimens examined, they continued latero- 

 dorsad from the base of the penis to fibrous attachment 

 upon either ischium though much less distinctly in males 

 that were inactive. Almost surrounding this crus of the 

 corpus cavernosum is the M. ischiocavernosus. Im- 

 mediately caudad is situated the large bulb (upon either 



