196 Bulletin American Museum of Natural History. [Vol. XXXIV, 
Table I.—Measurements of Species and Subspecies of Microsciurus. 
External Measurements Cranial Measurements 
{ ie 
2 ine) e S 2 2 og “ 
Se Seah S .8 1% (2 |) 23/248 2 
ee Se\s8|2| =| 2s) e8) 63 | 53/58 3 
52 ies |o5 i =| 30 Lo ae =f a aa 
Ze Ge uel ea aa Ae PS ee ae cl 
M. alfari alfari Type | 250} 145 | 105 | 36.5] Type | 36 22, LS 19 10 
M. alfart venustulus es 250 | 148 | 102 | 40 = oF 23.2| 14 biG 10.5 
M. alfari browns a 260 | 140 | 120 | 38 - 36 21..2;12.4| — / 11 
M. boquetensis i 257 | 141 | 116) 37 a — — |14 — —_— 
M. similis similis 5 250 | 127 | 121 | 33 4 35.41 20.5) 13.4) 17.7110 
M. similis fusculus Type | 234/| 126/108 | 35 None; — — rare 4 —— 
M,. simonsi EG 250 | 138 | 112) 38 Type | 38.8/ 23.5) — — — 
M. otinus a 242 | 130/112) 36 © Hs — | 22.7|13.3| — | 10 
M. isthmius isthmius ‘ — |150| — | 37 s — | 22 14.3/18 10 
ms i o 3 243 | 137 | 110} 36 4 Bove 21 Oi too | be. | 10.2 
M, isthmius vivatus Type | 260 | 147 | 113 | 38 Type. | 38.2} 22.5 1)13.4/.18 10.7 
." a os 2 top. | 239 | 129/ 110| 36 — — — — = — 
M. mimulus Type | 239 | 130 | 109 | 36 Type | 38 23 13.5| — | 10.6 
fe ve ve 246 | 136 | 109 | 36 4 39.5) 22.7): 14 18.9/ 10.9 
M. palmeri 8 270 | 149 120} 40 4 Stee) oi 4)| 1o.4).18.1) 10.7 
M. peruanus Type | 240} 130} 110] 38 Type | 35 21.23 13 18 9 
M. napi ag — | 157| — | 37 ek: — | 21 13 — 9 
M. rubrirostris < 278 | 145 | 133 | 38 oe 37 22 13.3 7.18:.5|.10 
. : t S10) 1601501 40° “Vr top. 737) 23 13..4-/ 19 “1-10 
M. florencie Type | 270! 150! 120| 40 Type | 40 23.71 14 19 10 
a e 3 273 | 143 | 130 | 40 3 38 22.8, 13.31 148.8) 10 
Genus Sciurillus Thomas. 
Sciurillus Tuomas, Abstr. Proc. Zool. Soc. London, No. 133, p. 36, May 12, 1914; 
Proc. Zool. Soc. London, 1914, p. 416, June, 1914. Cf. also THomas, Ann. and Mag. 
Nat. Hist. (8), XIII, p. 575, June, 1914 (incidental reference). 
Type, Sciwrus pusillus Desmarest; or, “should any doubt be thrown 
on the determination of Sciurus pusillus, the genus should be considered as 
founded on the species represented by the type of S. kuwAlii” (Thomas, I. ae 
“Postorbital processes over posterior root of zygoma. Interorbital 
space as broad as the braincase. Zygomata very broad and strong. Ante- 
orbital foramen small, far in front of the teeth, as in Nannosciurus, its open- 
ing continued upwards as a peculiar curved groove along the front edge of 
the anteorbital fossa. | 
“ Cheek-teeth 3, as in Nannosciurus. Molars low, as in other Nanno- 
sciurine, their set normal, as in Nannosciurus, the last molar not facing 
outwards as in Myosciurus. Their upstanding cusps, both above and below, 
