50 BULLETIN 43, UNITED 8TATES NATIONAL MUSEUM. 



peculiarity is less marked in the young adult than in some of the older 

 animals. 



Mandibular teeth. — Tlie incisors are contiguous, blunt, uniform — an 

 intervalexistinghetween the anterior and posterior borders of thecutting" 

 edges. Canine excavate posteriorly touching the triangular com- 

 pressed simple first premolar. The second premolar is a third higher 

 than the first. Tlio cinguhim is slightl\ elevated at the base of the 

 main cusp (paraconid) and provided Avith a small heel (hypoconid). 

 The first molar much larger than the second, quadrate tapering 

 slightly fiU'ward. Protoconid marginal, compressed, sectorial, less 

 than twice the height of hypoconid and expanded at base anteri- 

 orly. Paraconid trifld, the main cusp conoidal not distinct from cin- 

 gulum, marginal hypoconid comi)ressed. Entoconid conoidal, conspic- 

 uous, marginal, an intermediate tubercle between it and the paraconid. 

 Second molar quadrate, tapering slightly backward. Protoconid not 

 marginal, but a well defined nearly comi)lete ciugulum at buccal base, 

 conoidal, with flange at base anteriorly, paraconid obscurely trifid, the 

 main cusp nnich thelongest, hypoconid sectorial, entoconid conoidal, 

 no intermediate tubercle between it and paraconid. The third molar 

 rudi mental scarcely larger than one of the lower incisors; blunt, de- 

 pressed in center of grinding surface; sometimes provided with a par- 

 tial cingule. 



The milk incisors are retained for a longer time than the other milk 

 teeth. They may remain in the jaw, lying to the labial side of the 

 complete set of permanent incisors. 



BemarlxS. — I am not certain about the identification of some of the 

 cusps of the molar teeth in Artibcm. Individual variation occurs in 

 the arrangement of the cusps on the lingual aspect of the first and 

 second mandibular molars, which make it likely that they are develop- 

 ments from a ciugulum in a tooth from which all traces of the true 

 cusps have disappeared. If this hypothesis be accepted the description 

 is greatly simplified. But it lacks inoof, and demands for Artibeus a 

 more abberant position than is suggested by other features in its 

 economy. 



The loss of the Vlik<^ cusps of the molars, the de\'el()pment of mar- 

 ginal cuspules, the delicate and sojuewhat elaborate sculpturing on the 

 grinding surfaces combine to the make these teeth of Artibeus unique.* 



Alter framiug the above description I studied the te(;tli iu the allied genera Cen- 

 iurio, Stm-nira aud BrachijphyUa. Those notes are herewith appended: 



Centurio — The mandibnlar molars suih as in Jrtihciis. The canine deeply cou- 



*The following notes on the teeth of allied genera will he of value. In Dermanura 

 the lower incisors ai-e twice the length of the same teeth iu Artibeus and Uroderma. 

 The upper central incisors in the genus last named are much longer than the laterals, 

 and are furnished with oblique cutting edges much iu the same manner as in Hemi- 

 dermaand Vavipyrops. Artihcus, Devmnnura, atid Uroderma, are readily distinguished 

 from rampijropn by the presence of a marginal cusp (protocouid) on the auteriop half 

 of the lingual aspect of the first lowey Riolar, 



