the sarcophagous Marsupialia or to the Insectivora. It has, how- 

 ever, decided resemblances in the form of the molars, and in the 

 deficiency in the number of the inferior incisors, to such genera 

 of Insectivora as My thorny s and Solenodon, while in the large 

 canines, it more nearly approaches Sarcophaga and Garnivora. 



I propose to include the genera Ambloctonus, Oxysena, Stypolo- 

 phas, and Didymictis in a special division under the name of 

 Greodonta. This division may be regarded as a suborder of the 

 Insectivora. It is possible that the genus Diacodon Cope belongs 

 here also ; its species resemble Chiroptera in the inferior dentition, 

 and are of small size. The genus MesonyxJ which I discovered 

 in the Bridger beds of Wyoming, cannot be referred to the Greo- 

 donta as here constituted, since the trochlear face of the astragalus 

 is completely grooved above as in the true Carnivora, and its 

 distal end presents two distinct facets, one for the cuboid and the 

 other for the navicular bones. It represents on this account a 

 peculiar family, the Mesonychidae. 



To the Greodonta must be referred the genera Pterodon and 

 Palseonictis of De Blainville, from the French Eocene. This 

 author and Pomel placed them in the Marsupialia, but Professor 

 Gervais remarks (Greologie et Paleontologie Francaise) that the 

 evidence is insufficient for such a course. Here also doubtless 

 belong supposed Garnivora from the Wyoming Eocene, stated by 

 Marsh to be allied to the Viverridae. 



The remarkable type first introduced to the notice of paleonto- 

 logists by Leidy, represented by the genera Anchippodus, Ecto- 

 ganus, etc., has been looked upon as an order of Mammalia by 

 Marsh, and termed the Tillodontia. He gives, 2 as its characters, 

 the possession of claws, plantigrade feet with five toes, a third 

 trochanter of the femur, and separate scaphoid and lunar bones. 

 Also, that the dentition is characterized by " molars of the ungu- 

 late type," small canines, and large scalpriform incisors in both 

 jaws, faced with enamel and growing from persistent pulps as in 

 the Rodentia. He says this order " seems to combine characters 

 of the orders of carnivores, ungulates, and rodents." 



Except in the dentition, the definition above given applies to 

 the Greodonta ; and an analysis of the dentition shows so many 

 points of resemblance as to render it probable that they pertain 

 to the same order of Mammalia. Also, except in the dentition, 

 the characters given by Prof. Marsh do not differ from those of 

 the Insectivora. The structure of the superior molars is not in- 

 consistent with the same order, and the small canines and large 

 incisors are even more like those of most Insectivora than are 

 Greodonta. The singular form of these incisors, and their growth 

 from persistent pulps, is rather characteristic of Rodentia. The 

 transverse or tubercular premolars also distinguish this group 

 from both the Greodonta and the true Insectivora. The defini- 

 tions of the order and sub-orders will then be as follows: — ,, 



1 Ann. Rept. U. S. Geol. Surv. Terrs., 1872, p. 550. 



2 Amer. Journ. Sci. Arts, 1875, 231. 



