1889.] ** [Allen. 



incisors are very small and are free from both the central incisor and the 

 canine. The first premolar is distinctly caniniforin and does not touch 

 either the canine or the second premolar. 



The mandibular second premolar does not touch the third premolar. 

 The distance from the anterior border of the canine to the first molar is 

 3 mm., a distance over | mm. greater than that from the anterior border 

 of the canine to the central incisors. 



Measurements. mm. 



Head and body (from crown of head to base of tail) 44 



Length of arm 25 



" forearm 32 



First dio-it { Length of first metacarpal bone 4 



I ' ' first phalanx 3 



S d d* 't ( Length of second metacarpal bone 26 



( " first phalanx 3 



f Length of third metacarpal bone 32 



Third digit.... first P' la ! a " x " 



second phalanx 20 



third phalanx. . 10 



f Length of fourth metacarpal bone 30 



Fourth digit... J first phalanx 13 



(. ft second phalanx 11 



f Length of fifth metacarpal bone 32 



" first phalanx 11 



(. " second phalanx 10 



Length of head , 15 



Height of ear 15 



tragus 6 



Length of thigh 11 



tibia 13 



foot 10 



' ' interfemoral membrane 15 



tail 8 



Costa Rica. Collections of National Museum. Collected by J. C. Zele- 

 don. 



The nine specimens of O. brevicauda, which formed the basis of my 

 study, were chiefly interesting from the measurements which were made 

 of the peripheral parts. These are arranged in tabular form (p. 22). 



