NYCTOMYS. TVLOMYS. 217 



Measurements. Total length, 250-260; tail vertebrae, 120-125; 

 hind foot, 25; ear, 17. Skull: basal length, 28; occipito-nasal length, 

 32.4; zygomatic width, 18; mastoid width, 13; interorbital width, 

 it ; length of nasals, 10.6; width of nasals, 3.2; length of palatal 

 slits, 4.6; width of palatal slits, 2.2; length of palate to palatal notch, 

 12.4; length of upper molar series, 4.8; length of single half mandible, 

 18. (Bangs, 1. c.) 



45. Tylomys. 



Tylomys Peters, Monatsb. K. Preuss. Akad. Wiss. Berlin, 1866, p. 

 404. Type Hesperomys midicaudus Peters. 



" Ears rather large, naked ; tail and soles of feet naked. Skull with 

 no raised supraorbital ridges, but with a broad horizontal edge over 

 orbits; antorbital foramen not visible from above." 



KEY TO THE SPECIES. 



A. Broad horizontal edge above orbits; ears 



large, naked; tail long. PAGE 



a. Upper parts ferrugineous ................ T. nudicaudus 217 



b. Upper parts dark gray .................. T. tumbalcnsis 218 



c. Upper parts pale gray? Specimen too 



young to characterize .................... . . T. bullaris 219 



d. Upper parts rufous fawn and black .......... T. watsoni 219 



e. Upper parts mouse color and black ....... T. panamensis 219 



195. nudicaudus (Hesperomys}, Peters, Monatsb. K. Preuss. Akad. 

 Wiss. Berlin, 1866, p. 404, pi. i, figs. 1-4. 



X A RED-TAILED RAT. 



Type locality. Guatemala. 



Geogr. Distr. Southeastern Mexico (State of Chiapas), into 

 Guatemala. 



Color. Upper parts ferrugineous, base of hairs plumbeous, under 

 parts white; tail naked, basal half black, remainder yellow; hands 

 and feet dusky. 



Measurements. Total length, 403.75; tail, 207.5. Skull: occipito- 

 nasal length, 46; Hensel, 38; zygomatic width, 24; interorbital con- 

 striction, 8.6; length of nasals, 14.8; palatal length, 19.3; length of 

 mandible, angle to alveolus of incisor, 35; length of upper tooth 

 row, 8.6. 



