1895.] *^' (Cope. 



compressed crowns, besides the external row. Posteriorly the marginal, 

 and the third row (from without) disappear, and the second and fourth 

 approximate, and end in a single tooth in line with the second row. 



In one of the specimens the cranial roof posterior to the orbits can be 

 lifted oflF. Above the sphenoid region, viewed from above, there are four 

 ^ubround tuberosities, which look like the casts of cavities. On the infe- 

 rior side of the roof in the corresponding positions are four flat tuberosities, 

 of somewhat different form from the inferior ones, and an obtuse median 

 prominence, which fits into the space between the four inferior tuberos- 

 ities. These superior tuberosities resemble the casts of cavities left by the 

 dissolution of two hemispheres, and two transversely expanded larger, 

 mesencephalic lobes, with a hypophysis between them. This interpre- 

 tation is, however, very uncertain, especially as the structure does not 

 resemble the cast of the cranial cavity whicli I have previously describ€d 

 in Empedias. 



Measurements. mm. 



Length of cranium on middle line 76 



Width of cranium posteriorly 63 



Anteroposterior diameter of orbit 16 



luterorbital width 13 



Width between nares at front of muzzle 9 



Diameter of largest maxillary tooth 2.5 



Length of long preraaxillary tooth 7 



Diameters mandibular ramus at fourth tooth •< ^ ^ 



*. transverse. . 9 



From the Permian of Texas. 



Pakiotichus aqoti. Ectocynodon aguti Cope, Proceeds, Amer. Fhilos. 

 tioc, 1882, p. 451., PI. vii. 



Since this species was described, I have received six crania from the 

 same horizon. These include some specimens of smaller dimensions 

 than the type, while others are intermediate, and one is a little longer. 

 They all agree in their wedge-shaped form with less posterior width than 

 the /'. isolomus, since it is only three-fourths the length. The posterior 

 border is openly emarginate posteriorly, while it is nearly straight in the 

 P. isolomus. The cranium has a less depressed form, especially posteri- 

 orly. In one specimen, which is much flattened by pressure, the pro- 

 portion of width to length remains unchanged. In the sculpture, the 

 longitudinal lines are not relatively so conspicuous. The reticulation is 

 conspicuous on the middle parts of the superior surface throughout, and 

 on the sides posteriorly. The sculpture is very fine on the jugal bone 

 and the sides of the muzzle. There are four teeth on the premaxillary, 

 and fifteen in the external series of the maxillary, of which in some 

 specimens the third from the front is the largest, in others the fourth. 

 The crowns of the teeth of the internal series are compressed so as to be 



PROC. AMER. PHILQS. SOC. XXSIV 149. 3 E. PRINTED FEB. 18, 1896. 



