[October, 



little 



The Periptychid/e.— The structure of Periptychus has re- 

 mained uncertain so far as regards the limbs and feet. As these 

 parts have much significance, I point out some of their characters 

 as seen in specimens recently received from the Puerco beds. 



The brain is, as in Phenacodus, very small, with the olfactory 

 lobes widely separated from the small hemispheres. The humerus 

 has an epitrochlear foramen. The astragalus has no trochlear 

 groove, and the neck is short. The head is convex, and presents 

 a lateral face for contact with the side of the cuboid. Five digits 

 on the posterior foot. The lateral ungues are rather narrow 

 hoofs. Cervical vertebrae very short. 



The absence of trochlea of the astragalus is a point of resem- 

 blance to Meniscotherium, and separates Pcri*tychus x from the 

 Plicnacodontidce as a family type, which I call the Periptyo'ddtC. 

 With it must no doubt be associated Anisonchus Cope, Haplo- 

 conns, and the following new genus. 



Ilcmithlccits ko:ca/evskiaiins, gen. et sp. nov. Char. gen. — Denti- 

 tion of the type of Anisonchus, but there is but one internal tuber- 

 cle of the superior true molars, which is the apex of the V, the 

 posterior cusp being absent, no intermediate tubercles. Last and 

 penultimate premolars with internal cusp. Last inferior true molar 

 with heel. 



Char, specif.— The internal lobes of both third and fourth 

 premolars are conic. The true molars are distinguished from 

 the species of Anisonchus and Haploconns in that the posterior 

 cingulum does not develop an internal cusp. Instead of this, 

 the apex of the median V forms the internal angle of the crown, 

 and an anterior and a posterior cingula of equal size rise to meet 

 it. The inferior molars have anterior and posterior median cusps, 

 and the internal anterior cusp is not compressed. Length of P- m. i v 

 with true molars, .0185 ; diameters P-m. iv, anteroposterior, .005 J 

 transverse, .007; do. of M. 11, anteroposterior, .0046; transverse, 

 .007. The last true molar is smaller than the first or second. 

 Two individuals from the Lowest Puerco. Larger than A. 

 sectorius. Dedicated to the distinguished palaeontologist, Dr. W. 

 Kowalevsky, at present traveling in this country. 



In the August number of the Naturalist it was shown that 

 there are species of Haploconns with the interior lobe of the 

 fourth premolar conical. I now find a species of Anisoucfius 

 which presents the same peculiarity. I describe it as follows : 



Anisonchus coni/erus, sp. nov. — Three individuals of larger size 

 than the H. kow ih vskianus. This species differs materially from the 

 last in the larger development of the cingular internal cusp of tne 

 superior true molars, so that the transverse diameter of the latte 



^Catathheus was established on the permanent dentition of Periptychus. 



