200 



Wortman — Studies of Eocene Mammalia in the 



3G 



especially noticeable in the ulna, femur, patella, navicular, 

 calcaneum, and cuboid. These resemblances, however, may 

 be accidental and deceptive, and. until we can connect the two 

 groups somewhat more closely in point of time, their relations 

 cannot be regarded as finally settled. 



In this connection I wish to draw attention to three genera 

 described by Professor Marsh from various fragmentary 

 materials (mostly teeth and portions of jaws), the validity of 

 which is either questionable or the remains are insufficient to 

 indicate their true position. They are as follows : 



Triacodon fallax Marsh.* 

 The type of this genus and species, figure 36, consists of the 

 anterior portion of a tooth crown of the first lower molar or 

 sectorial, which agrees in every particular 

 with the corresponding tooth of Viverravus 

 gracilis. I therefore do not hesitate to refer 

 it to this species. Professor Marsh errone- 

 ously supposed that it was an entire tooth 

 of the premolar series, and this at first sight 

 would seem possible, since the broken sur- 

 face where the heel joins the trigon is worn 

 in such a way as more or less to conceal the 

 fracture. I give herewith a cut of the tooth 

 seen from the inside. 



A second species, T. gvandis,\ was also described by Pro- 

 fessor Marsh, and this again is founded upon the trigon of a 

 sectorial molar of some larger species of Carnivore, presuma- 

 bly Limnocyon verus, although the specimen agrees equally 

 well with some other species, notably Sinopa agilis. A third 

 species, T. nanus, is of the same character, and is referable to 

 some small carnivorous or insectivorous species. 



Ziphacodon rugatus Marsh.J 



This genus and species was 

 established upon the anterior 

 portion of a lower jaw, figure 

 37, carrying the second and 

 third premolars with the roots 

 of the first and fourth, together 

 with the alveolus for the canine 

 and a part of that for the first 

 incisor. As far as one is able 

 to judge, this jaw fragment 

 agrees perfectly with Viverra- 



Figure 3 6.— A 

 right lower sectorial 

 of Triacodon fallax 

 Marsh ; inside view ; 

 natural size (Type.) 



37 



Figure 37. — Left lower jaw of Zipliac 

 odon rugalus Marsh; outside view 

 three halves natural size. (Type.) 



*This Journal, vol. ii, August, 1871, p. 15, separata. 

 \ This Journal, vol. iv, August, 1872, p. 32, separata. 

 JThis Journal, vol.iv, August, 1872, p. 25, separata. 



