88 
BULLETIN 57, UNITED STATES NATIONAL MUSEUM. 
Genus RHYNCHISCUS Miller. 
1823. Proboscidea Spix, Simiarum . et Vespertilioiiuin Brasil. Spec. Nov., 
p. 61. (Not Proboscidea J. G. Brugiere, 1791.)' 
1867. Rh ynchonycteris Peters, Monatsber. k. preuss. Akad. Wissenscb., 
Berlin, p. 477. (Not Rhinclionycteris Tschudi, 1844-46.) 
1878. Rliynchonycteris Dobson, Catal. Cliiropt. Brit, Mus., p. 366. 
1904. Proboscidea Allen, Bull. Amer. Mus. Nat. Hist., XX, p. 343, October 8, 
1904. 
1907. RhynchiscHS Miller, Proc. Biol. Soc., Washington, XX, p. 65. June 12, 
1907. 
Type-species— Proboscidea saxatilis Spi ^=V espertilio naso Wied. 
Geographic distribution— The mainland of tropical America. 
Number of forms. — Only one species of Rhynchiscus is now known. 
Characters. — -Dental formula : 
-2-. 1. - 2-4 5 6 7 .1 -1 
...... 1 zl 
1 ■ — 2-45 6 H 3-3’ 1-1’ 
pm 
2-2 
m 
3-3 
: 32. 
2-2’ ■ ' 3-3 
Upper incisor minute, simple, persistent, inserted in main axis of 
premaxillary and at extreme tip of bone, the 
teeth, therefore, converging. Lower incisors 
small, trifid, forming a continuous, slightly 
concave line between canines. Canines and 
lower premolars as in Emballonura. Anterior 
upper premolar (pm 2 ) unusually large, its 
crown sharply pointed and noticeably flat- 
tened laterally, the outline being nearly an 
isosceles triangle. First upper molar with 
conspicuous antero-external cusp separate 
from small parastyle. Hypocone of m 1 and 
m 2 very distinct, subterete. Third upper 
molar with well-developed metacone and 
three commissures. Lower molars all alike 
in form, the third merely smaller than the 
others, all the cusps normal. Skull (fig. 13) with rostrum somewhat 
more than half as long as brain case, and so deep posteriorly that the 
forehead forms scarcely any angle with upper surface of rostrum. 
Lachrymal region slightly inflated. Premaxillaries short, very broad 
posteriorly, extending to upper surface of rostrum. Basisphenoid 
pits deep, their outer border sharply defined; but on inner side they 
merge into each other without dividing ridge. Audital bulla slightly 
larger than the two pits together. Mandible very abruptly bent 
upward behind tooth row. Externally characterized by the greatly 
elongated muzzle, and among the American genera by the absence of 
wing sacs. The only known species has the forearm sprinkled with 
Fig. 13.— Rhynchiscus naso. 
Adult male. Escondido 
River, Nicaragua, 50 miles 
fromBluefields. No. 51565. 
X2. 
