104 



osborn: oligocene, miocene, pliocene EQtrnwE. 



Topotypes.— Numerous fragments of upper and lower jaws, teeth, and skeletal material, mostly isolated, Amer. 

 Mus. 14187, from the same locality. 



Type figure— Plates 13.3, 14.2,4, text Fig. 78 of this Memoir. 



Characters. — (Matthew, 1913) (1) An animal of smaller size than the type of M. isoncsus secundus, about equalling 



Fig. 78. Type of Mcrychippus isoncsus primus Osborn, Amer. Mus. 14187. Crown and side view of upper and 

 lower dentition. All figures natural size. 



in size the type of M . seversus. (2) Crochet apparently single, i. e. no pli caballin, separate from protoloph except in well 

 worn teeth; (3) protocone elongate transversely, strongly united with protoconule at an early stage of wear; (4) usually 

 a single enamel fold projecting from metaloph into prefossette and a single fold projecting into postfossette. (5) Limb 

 and foot bones slender. 



The large number of topotypes from the same level agree very well with the type characters. 



