16 ANATOMY OF THE WOOD EAT 



dontomys 27.5 mm.; Neotoma 28 mm.; and Teonoma 29 

 mm. The width of ear, given in the same order, is 22.5, 

 22, and 25 mm. Hairiness of this member shows individual 

 variation, and variation with age as well. In Teonoma 

 the ears of juveniles especially are better haired than in 

 adults. Hairiness of ear is moderate in all cases, but in old 

 individuals of Homodontomys and Neotoma this member may 

 be practically naked. There is usually a shght covering 

 composed of very fine buffy hairs along the helix, and a 

 sprinkling of slightly darker hairs upon the terminal third 

 or two-fifths of the pinna. The antitragus is double and 



N VtNN/\ 



TMt^^W^ — ft NT > H tux 

 -TR^&ViS 





Fig. 2. Details of external ear of Homodontomys 



but shghtly indicated (fig. 2), nor is the tragus strongly 

 formed. The subhelix consists of a light cartilaginous fold 

 well within the conch, and the antihelix takes the form of a 

 low ridge. Variation in the form of the ear between the 

 three subgenera is not appreciable. 



In all females of the genus Neotoma there are two pairs of 

 inguinal teats, located close together and somewhat sug- 

 gestive of the mammae of a young heifer. 



Ventral dermal gland. As previously mentioned the males 

 of Teonoma exhibit a thickened dermal area midventrally 

 which may have a width of 70 mm. and a breadth of 35 mm. 



