CKEODONTA. 741 



adoption of a new general term for a group comp'osed of subordinate divis- 

 ions which have themselves already received names. 



DISSACUS Cope. 



Antea, p. 344. 



A portion of the skeleton of Dissacus carnifex (antea, p. 345) includes 

 the superior molar teeth, with some vertebrae and bones of the limbs. I 

 take the present opportunity of making the description of that species more 

 complete. 



The general character of the superior molars is that of Mesonyx, but 

 the cusps are more compressed. The last superior molar resembles the 

 others in having a second cusp posterior to the principal one, which is not 

 present in Mesonyx ossifragus. The last and penultimate molars are of the 

 same size in this species, while the first is a little smaller, and the fourth 

 premolar is much smaller. The last-named tooth differs from the true 

 molars in not having a second external lobe, but instead, a large heel; also 

 in the small size of its internal lobe. The anterior base of the crown is a 

 little produced, but there is no tubercle. The same is true of the first true 

 molar, but in the remaining true molars the anterior edge is recurved, so as 

 to be a transverse low tubercle. The internal cusp is, in all the true molars, 

 subconic; rounded on the internal face, and flattened on the external. The 

 true molars have a posterior cingulum, which is small on the first, but 

 strong and recurved on the second and third. There is an obtuse rib-like 

 external cingulum on the second and third molars, but no internal cingulum. 

 Enamel minutely roughened; smooth where used. 



Measurements. 



M. 

 Length of last four molars 0475 



Diameters of P-m. ^ *°^«™P°«<^^"°^ 0105 



( transverse 0065 



K anteroposterior Oil 



I''*'"**^" °f *1- M transverse 0085 



Diameters of M."- 5 anteroposterior 0130 



.j<a. 

 < tr 



iii \ ^' 



I ti 



transverse '. .. .010 



Diameters of M. m ^ anteroposterior 0110 



transverse 01'25 



Length of last three inferior molars 036 



