218 THE WASATCn A^'D BKIDGER FAUNiE. 



Tlie ramus of the jaw is more slender than in M. gracilis, and tlie last 

 true molar has quite a ditierent form. Instead of being- shorter than in 

 allied species, this tooth is rather longer, evidently in consequence of a 

 well-developed heel. The fourth premolar has a strong inner tubercle, and 

 no anterior cusp or cinguluni. Its heel has an elevated posterior border, 

 inclosing a fossa with tlie principal cusps. No external or internal cingula. 

 Third premolar with two roots. Alveolus of the second, large and appar- 

 ently simple ; it is filled with matrix. Canine large, directed forwards, and 

 occupying all the space between a short diastema and the symphysis. The 

 latter extends posteriorly to below the anterior part of the third jiremolar. 

 The ramus is compressed and maintains an equal depth to the end of the 

 molar series. Its inferior border descends below the coronoid process, and 

 is not incurved, but the external face is convex. The anterior masseteric 

 ridge is well marked, descending to below the middle of the ramus. Mas- 

 seteric fossa flat. Mental foramen below the third premolar. 



Measurements. 



u. 



Length of the fragment of raniim 04.'55 



Length of dental series witlioiit incisors 0280 



antero-jioHterior 0040 



Diameters of canine < ^ „^„ 



{ transverse 00"^ 



Length of premolar series 0100 



Length of fonrtli premolar 0040 



Width of fourth premolar l>ehind 0(W 



Length of true molar series 0136 



Length of last true mol.ar 0052 



Width of last true molar anteriorly 0030 



Depth of ranins at third jjremolar 0090 



Depth of ramus at last molar 0090 



This species is dedicated to my friend Prof. WilHam B. Scott, of the 

 College of New Jersey. 



TOMITllEKIUM Cope. 



Third Account of New Vertebra t a from tli<- Hridgrr Ko( cue of Wyoming, p. '2, August 7, 1W2 ; Proceed- 

 ings American Philosophical Society tor 1H72 (pulilishcd .laiiuary, 1H72) ; On the Primitive Types 

 of Mammalia Educahilia, 1873, May 6, p. 2; Animal Kcjiort U. S. Geol. Surv. Terrs., 1872, p. 

 456 (1873). 



Dental formula of the inferior series: I. 2; C 1 ; Pm. 4; M. 3. The 

 last molar has an expanded heel. The third premolar consists of a cone 

 with posterior heel; the fourth premolar exhibits, besides its principal cone, 

 an interior lateral one, and a large heel. The true molars support two 



