bangs: chikiqui mammalia. 27 



Anion" tree squirrels, Syntheosciurus brochus has no very near ally ; its 

 licht, papery skull recalls that of Sciuropterus, but the audital bullaj are much 

 smaller. Its peculiarly straight, slender rostrum, weak, projecting, and 

 grooved incisors at once distinguish the genus from any other. 



Mus rattus Linn. 

 One youngish 9 , Boquete, 4,800 ft. Mar. 



Megadontomys ^ flavidus,- sp. nov. 

 Type. —Mus. Comp. ZooL No. 10,331, ad. J, Boquete, April 12, 1901. 4,000 ft. 



Twenty-seven specimens, Boquete, 3,000 to 5,000 ft., February and April. 



Characters. — A large species, much paler and yellower than M. thomasi 

 Merriam, Mountains near Chilpancingo, Mexico, 9,700 ft., and M. nelsoni 

 Merriam, Jico, Mexico, altitude 6,000 ft. ; skull with much more rounded and 

 elevated and less flattened brain case; palatal slits very wide ; audital bullai 

 decidedly small ; ears small. 



Color. — Upper parts brownish cinnamon, usually rather more rusty toward 

 rump, brighter, inclining toward orange-buff along lower sides ; a large, con- 

 spicuous blackish patch on each side of head at base of whiskers ; whiskers 

 mixed black and colorless; underparts white, the gray basal portion of the 

 hairs showing through ; a slight collar yellowish or buffy ; feet and hands 

 whitish, marked with brown about ankles and wrists ; tail sparsely clothed 

 with short stiff hairs, dusky above, grayish below ; ears nearly naked, dusky 

 outside, slightly silvery inside. Young examples differ from the adults in lie- 

 ing darker and duller brown above ; the under parts more grayish, less purely 

 white. 



Measurements (of ten adults, type and topotypes) — 



1 Though described by Dr. Merriam as a subgenus of Peromi/sctts, Meqadontomys 

 is entitled to generic rank, on account of the unwieldy proportions of Peromyscus. 



2 Flavidus, yellowish. 



