32 



KANSAS UNIVERSITY QUARTERLY. 



Deciduous dentition. 



The lower molars are compressed and elongate, and the cusps are 

 prominent. The first two are nearly alike, with a single ridge, t"he 

 two elongated cusps of which are united nearly to the apex, and with 

 a groove between them in front. The inner cusp of the first molar 

 is situated a little in advance of the outer. The apex of the cones 



of both stand a little in ad- 

 vance of the union of the two 

 roots. The posterior basal 

 ridge is broader than the an- 



p. leptorhinus w. Milk molars and first terior, and, like that, has 

 permanent molar 



minute tubercles. The third molar has three ridges, 

 the middle one standing over the arch between the two 

 roots. Their confluent cusps do not differ from those 

 of the preceding ridges, save that their base antero- 

 posteriorly is a little narrower, and the deeper groove 

 between the apices of the third is behind; the first ridge 

 has a small low tubercle in front of the middle, united 

 with the ridge; the anterior basal ridge in front is very 

 narrow, while that behind is only a little broader; there 

 is no lateral ridge at the base of the transverse ridges. 



The upper molars are decidedly broader than the 

 ^j^ lower molars, and have a very distinct lateral basal 

 Lower molars, ridge. The first two are distinctly broader in front than 

 behind, and the cusps of all the ridges are separated by a deeper 

 interval from each other, the cusps themselves scarcely differing in 

 height. The two cusps of the first molar have each a rather sharp 

 ridge running upward and forward to near the edge of the basal 

 ridges; behind, the outer cusp only has a similar ridge which curves 

 upwards and inwards to the end near the middle of the basal portion, 

 at a little distance from the edge. The cusps of the two pairs of 

 ridges of the second molar are simple cones or pyramids, with a 

 moderately deep notch between them, and with a deep valley between 

 the ridges. The basal margin in front is a trifle broader than that 

 behind, and the anterior ridge is distinctly shorter than the posterior 

 one. The third molar differs but little from the second, except that 

 the outline is more nearly square, and the anterior ridge is as long as 

 the posterior one. 



The canines both above and below are similar, elongate, and less 

 broad than the newly erupted successors; they are smooth through- 

 out, and everywhere nearly uniformly oval in outline. 



The incisors have the worn surface more nearly vertical than their 

 successors. 



