38 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Reithrodontomys australis vulcanius, subsp. nov. 
Type. — Mus. Comp. Zool., No. 10,281, ad. g, Volcan de Chiriqui, May 26, 1901. 
10,500 feet. 
Characters. — Pelage extremely long and silky; colors much darker and 
crayer than in true RA. australis; skull heavier, especially rostral portion; 
palatal slits longer and wider. 
Color. — Broad dorsal band strong sepia, paling off on sides to isabella 
color, somewhat shaded with cinnamon; top of nose and head paler, grayer 
than back; under parts isabella color, strongly shaded with cinnamon between 
arms and about vent; feet and hands grayish; ears well haired, sepia (about 
the same shade as darker parts of back); tail well clothed with short, close 
hairs dusky above, grayish below. . 
16. x 13 tie Oe 
Fies. 16 anv 17. Reithrodontomys australis vulcanius. Type. 
Measurements. — Type, adult @, total length, 170; tail vertebre, 95 ; hind 
foot, 19; ear, 14. Skull, basal length, 19.4; occipitonasal length, 22.8; zygo- 
matic width, 11.4; mastoid width, 11; interorbital width, 3.4; length of 
nasals, 8.2 ; width of nasals, 2.6; length of palate to palatal notch, 9.2; length 
of palatal slits, 5; width of palatal slits, 1.8; upper molar series, 3.2 ; length 
of single half of mandible, 11.4. 
Remarks. — R. australis vulcanius is a well marked alpine form, very differ- 
ent from true R. australis in color, and also in its exceedingly long, silky pelage. 
The skull is slightly different. 
