NO. 2034. BATS OF THE GENUS GL08S0PHA0A— MILLER. 417 



length the percentages of variation for the three forms are 3.1, 2 — , 

 and 1 .9. The greater apparent variation in breadth is due to the fact 

 that the widened region extends further forward in some individuals 

 than in others, thus probably causing appreciable differences in the 

 capacity of the brain case. While some of the narrower skulls bear 

 a slight resemblance to those of Olossophaga longiroslris the likeness is 

 superficial, since the relative lengths of rostrum and brain case are 

 always noticeably different in the two species. 



Teeth. — Like the skull, the teeth have already been sufficiently 

 described so far as their general features are concerned. Kegarding 

 the upper incisors and the premolars a few details are required. 



When viewed either from the front, from behind, or on the cutting 

 edge, the outer upper incisor of each pair is seen to be an obviously 

 smaller tooth than the inner. Exact comparison of bulk is difficult, 

 owing to the greater obliquity of the cuttmg edge of the outer tooth, 

 but the difference, perhaps chiefly due to these peculiarities in obliq- 

 uity, is always appreciable, the apparent size of the larger tooth 

 exceeding that of the other by one-fifth or one-fourth. It becomes 

 more evident as the cutting edges of the teeth wear down, in a few 

 individuals approaching the proportion of 1 to 2. Anterior upper 

 premolar narrowly elliptical in crown outline, the width at middle 

 about one-third the length, the outer and inner borders nearly par- 

 allel, the former usually a little concave, the latter apparently always 

 perceptibly convex; width of region in front of cusp less than that 

 behind, but contrast not conspicuous. Posterior upper premolar 

 with crown outlme, except in rare instances, unlike that of first, the 

 width at middle nearly half the length, the outer border and region 

 in front of cusp much as in the anterior tooth, but postero-internal 

 portion of crown so developed inward as to destroy the symmetry of 

 the outline. This postero-internal projection varies considerably in 

 extent; usually its border is rounded, though not infrequently it 

 forms an acute angle, while in rare instances it is sharply limited 

 posteriorly by an evident notch; cingulum in most specimens well 

 developed, though never forming a cusp. 



Measurements. — See under subspecies. 



Remarks. — Although the species as a whole is not invariably dis- 

 tinguishable from its allies by small size alone, this character is usu- 

 afiy diagnostic in northern South America, the only region where 

 two members of the genus (longirostris and the small typical race of 

 soricina) are known to occur together. Exact determination of 

 specimens is not practicable without recourse to cranial and dental 

 characters. 



In its three large races (antillarum, mutica, and valens) GlossopTiaga 

 soricina appears to present an instance of the independent develop- 

 ment of nearly identical characters in isolated localities so far apart 

 95278°— Proc.N.M.vol.46— 13 27 



