168 PROCEEDINGS OF THE ACADEMY OF [1883. 



July 3. 

 Prof. Edw. D. Cope in the chair. 

 Seventeen persons present. 



A paper entitled " Description of a New Hydrobiinoid Gastero- 

 pod from the mountain lakes of the Sierra Nevada, with remarks 

 on allied species and the physiographical features of said region," 

 b}" R. E. C. Stearns, was presented for publication. 



The death of Isaac T. Coates, a member, was announced. 



On some Fossils of the Puerco Formation. — Prof. Cope stated 

 that he had recently received from the Puerco beds of New Mexico 

 remains of a number of individuals of the extinct mammal he 

 had named Feriptychus ditrigonus} Besides jaws and teeth with 

 permanent and temporary dentition in good preservation, the 

 pelvis, femur and tibia are included in the specimens. These 

 show that the species must be referred to the genus Gonoryctes 

 Cope, and render it very probable that the genus belongs to the 

 family of the Periptj'chidae. The absence of ungual phalanges 

 preverts absolute certainty. The genus is near Feriptychus^ but 

 differs in the one root and simple conic crown of the second true 

 molar in both jaws, and the presence of cingular cusps of the 

 superior molars, exterior to the external tubercles. Gonoryctes 

 ditiHgonus has the molars of both jaws larger than those of the 

 G. comma, and there is less difference in size between the posterior 

 and anterior teeth than in that species. 



The following new species accompanied the above : 



Periptyghus coarctatus. This species represented by teeth 

 of the lower jaw, viz.: one incisor, three premolars, and two 

 molars, two of the latter imperfect. The characters of the species 

 are well marked in the premolar and molar teeth. The former 

 lack the anterior and internal ledges of the F. carinidens and F. 

 rhahdodoyi, having only a prominent ledge-shaped heel, besides 

 the principal conical cusp. The true molars lack the small 

 tubercle which is between the pair of threes Avhich compose the 

 crown. The adjacent cusps of the threes are connected by low 

 longitudinal ridges instead of oblique ones. The cusps themselves 

 are closer together than in the other species, especially those of 

 the anterior three, which are closely approximated. The anterior 

 one is small and low. The enamel is grooved as in the other 

 species. 



Diameters of crown of fourth premolar: anteroposterior, -0115 ; 

 transverse, '0115 ; elevation ^^worn), -010. Diameters of crown 



1 Proc. American Philos. Society, 1883, p. 465. 



