1897.] 



NATURAL SCIENCES OF PHILADELPHIA. 



39 



crown. The molars increase in size from the first to the third, the 

 last named alone having a marked posterior commissural cusp, 



though a faint rudiment of it 

 second. 



can be discerned in the first and 



Fig. 3. The Lower Teeth of Tar- 

 sius fuscus. 



The anterior eminence is seen in 

 all, though it is least conspicuous in 

 the first tooth. The large metaconid 

 is separated from the small hypo- 

 conid by a deep valley. The sharp 

 posterior commissure is continuous with the apex of the hypoconid. 

 In the first and second molars the commissure is straight and trans- 

 verse, but in the third tooth it is prolonged backward ; beyond it, 

 the swollen contour of the tooth projects and yields the impression 

 of being a supplemental cusp ; so that the series when viewed from 

 buccal aspect gives to the first and second molars two denticles, 

 while for the third molar there are three. A cingule is sharply de- 

 fined at the basis of the paraconid and metaconid. All the lower 

 teeth have cingula. In the incisors, canines and premolars they 

 are entire or nearly so ; in the molars they are buccal only. 



The Upper Teeth. — The conical central incisors are separated 

 from one another at their apical thirds. They are sharply worn on 

 the posterior surfaces and faintly 

 grooved on the outer. The lat- 

 eral is contiguous to the central, 

 but separated from the canine by 

 a narrow interval. The tooth is 

 minute, higher than the central, 

 its tip being on the level of the 

 cinsrulurn of the tooth last named. The canine is smaller than the 

 central incisor. The premolars abruptly increase in size from before 

 backward ; the first two are ridged on palatal surface like the ca- 

 nine ; the third alone presents on palatal surface a broad basal cusp. 

 The molars are trituberculate with acicular cusps. Slight indica- 

 tions exist of the beginnings of cusps (conules) on the commissures 

 uniting the protocone with the paracone and metacone. The ciugu- 

 lum is not complete in any of the molars, though nearly so in the 

 first and third. In the second no trace of it exists on the palatal 

 aspect of the second molar, the figure represents the line with too 

 much emphasis. 



Fig. 4. The Upper Teeth of Tardus 

 fuscus. 



