4 [January, 



The base of the inferior left canine was found in its socket ; the remainder was 

 found broken; the fragments were put together so as to make almost a complete 

 tooth, which presents no specific characters of any importance ; the anterior 

 margin is more rounded than in D. torquatus, and the grooves on the posterior, 

 external, and internal faces of the fang are deeper ; the young of D. torquatus 

 in the depth of the grooves agrees perfectly with our fossil, which, however, 

 from the wearing of the tooth, must have been an adult. 



The condyloid process of the right lower jaw was found broken off just below 

 the neck; in comparison with D. torquatus, it is less concave in its external out- 

 line, and there is a slight depression externally just below the end of the articular 

 surface ; the posterior face a little below the articular part is more compressed 

 and less flattened than in D. torquatus. 



The inferior extremity of the humerus is perforated ; the articular faces are in 

 no respect different from those of D. torquatus. 



The same is the case with the innominatum and the femur. 



Of the left posterior foot is preserved the calcaneum, the outer metatarsal, the 

 first and second phalanges of the outer toe and the first phalanx of the inner toe ; 

 all these bones completely resemble the corresponding parts of D. torquatus. 



As compared with Platygonus compressus, the calcaneum shows important 

 characters, which may be used in separating the bones of these animals, if they 

 should again be found mixed together. 



In Platygonus the astragalian face is not distinctly defined at its supero-external 

 part, but is confluent with the depression existing in that part of the bone 

 behind the fibular process. 



In Sus and Dicotyles this face is distinctly separated from the valley between 

 the two processes, and the inferior part of the astragalian process is much less 

 thickened than in Platygonus ; the whole bone is more slender and less flattened 

 than in Platygonus. 



My reasons for considering the cuboides figured by me* as belonging to Platy- 

 gonus, are as follows : 



From teeth there was evidence of two specimens of Platygonus of different 

 ages; portions of three calcaneal bones of the left side were found, two of which 

 were precisely similar ; the third is the one here mentioned as belonging to 

 Dicotyles. The larger of the two similar bones fitted perfectly with the ex- 

 tremity of a tibia, an astragalus and a cuboides forming a considerable portion 

 of the tarsus ; to this cuboides, however, the metatarsal bone above described 

 cannot be adapted. 



This will be the proper place for correcting an important error in the memoir 

 on Platygonus already quoted: on page 270, pi. 4, figs. 23 and 24, is represented 

 what was considered the iywier metatarsal. On comparison this bone is found to 

 correspond accurately with the inner right metacarpal of Dicotyles ; there are 

 two specimens of this bone, differing slightly in size, and the smaller one of 

 which has lost its lower extremity, and evidently belonged to a young animal. 

 We have therefore the same reason to refer this to Platygonus as the tarsal bones 

 above mentioned. 



I should also notice here, that the superior canines of very young Dicotyles 

 resemble very closely those of Platygonus, but are not so much compressed, and 

 have only a single angulated line at the anterior part of the base of the tooth. 



On account of the very strong resemblance between the dentition of Platygonus 

 and Dicotyles, I am inclined to consider the former as rather Suiline than Tapi- 

 roid in its affinities; the undulated outline of the lower jaw in the Dicotyles 

 group, reaches its maximum in the great dilatation of the angle of the jaw in 

 Platygonus ; the compression of the canines is carried to a greater decree than in 

 any other genus, and the molar structure is reduced to the simplest Pachydermal 

 form by the absence of all accessary tubercles. 



The dimensions of the fragments of Dicotyles depressifrons indicate an animal 



w- _ -- 1 



* Memoirs Am. Acad- of Science and Arts, New Series, Vol. 3, pi. 4, figs. 25,26. 



