1903 ] Mattheit\ Fauna of Titanotheriitvi Beds of Montana. 205 



small anterior and internal trigonid cixsps and strong basal heel. Pg' 



much smaller and simpler, with small heel and no other accessory 



cusps. P, is small and one-rooted, canine 



small, incisors small, suhequal. No dia- 



stemata except a slight one behind p,. 



Jaw rather deep in front. Second molar 



slightly larger than the first, third much 



smaller. 



Like the preceding genus, this 

 must be placed among the Zalamb- 

 dodonta, with no very near relatives p-.g.j. Microptemodiisboreaiis. 

 among living species, although it is .^:Sru?r!!i'?,Tnn^t"ewortLX- 

 not so strikingly different from mod- 

 ern types. Its nearest allies are also quite probably some of 

 the very inadequately described Insectivora from the Bridger 

 Basin, but neither it nor Apternodus can be considered as 

 possibly congeneric with any of the Bridger species, if Marsh's 

 descriptions are correct. 



Measurements. 



Lower jaw, m3 to incisive alveoli 12.4 mm. 



Lower teeth pj-mj S.4 



Lower m^olars m;_3 6.4 



Lower molar, nii longitudinal, at base 1.8 



" " " transverse 1.9 



" " '■ height of crown 2.7 



Ictops acutidens Douglas. 



A fragmentar}^ skull and jaws, with some limb-bones of one 

 individual, and the upper and lower molars of another, con- 

 firm and extend the characters of this species as indicated by 

 Douglas. 



The distinctions from previously described species are: 

 Dimensions fifteen per cent, less than any of the Leptictidae 

 from the Oreodon Beds. First upper premolar one-rooted, 

 two-rooted in I. dakotensis and hnllatns and in Leptictis hay- 

 deni. Supra-temporal crests widely separated anteriorly and 

 convergent posteriorly, instead of close together and parallel 

 as in all the later species. Upper molars and p'' more 



