EXTERNAL FEATURES 21 



situated between the ear and the eye, apparently never 

 exceeds one in number. Its usual length is 20 mm, in Neo- 

 toma, and 40 in Homodontomys and Teonoma. 



In a single individual dissected — a Homodontomys — there 

 was one vibrissa growing from a tactile papilla upon the 

 interramal area, caudad of the region of the symphysis 

 menti. In no other was this encountered, nor could it be 

 demonstrated in any of the numerous study skins upon which 

 I have searched for it. 



Situated on the caudo-ventral aspect of the distal fore- 

 arm, immediately above the wrist, are the carpal vibrissae 

 (fig. 1). These, too, grow from subcutaneous, tactile 

 papillae, are about 12 mm. in length, and vary from three 

 to nine in number. The minimum was encountered in 

 Neotoma and the maximum in Teonoma; but there seems 

 to be more individual than subgeneric variation in this re- 

 spect. It is extremely likely that they are tactile in 

 character. 



/o- 



