28 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Skull type, ¢ adult, basal length, 35.4; occipitonasal length, 40.2 ; zygomatic 
width, 19.6; mastoid width, 15; length of nasals, 17.8; width of nasals, 4.8 ; 
length of palatal slits, 7.4; width of palatal slits, 3.4; length of palate, to 
palatal notch, 17 ; to end of pterygoid, 24.4; length of upper molar series 
5.6 ; length of single half of mandible, 21.8. 
Figs. 5,6, and 7. Megadontomys flavidus. Type. 
Remarks. — The Volcan de Chiriqui is thus far the southernmost point from 
which a species of this well-marked group of Vesper Rats has been recorded. 
Megadontomys flavidus was common in the upland forest from 3,000 to 5,000 
