EDENTATA OF THE SANTA CRUZ BEDS. 43 



the supraorbital region many of the scutes are larger than elsewhere ; the 

 only sculpturing is a coarse pitting. 



The carapace in No. 15,957 (Plate VIII) consists of at least fifteen or 

 sixteen transverse movable bands and of eight fixed rows in the pelvic 

 buckler, though the latter is evidently not complete. The markings of 

 the scutes differ in the different regions of the carapace ; along the middle 

 dorsal region, for most, if not all of its length, the anterior exposed part 

 of each scute is quite smooth, except for a number of small, irregularly 

 placed pits, but much the greater portions of the exposed part is rather 

 coarsely punctate and has three longitudinal ridges, of which the median 

 is the narrowest and most convex, while each of the laterals is interrupted 

 near the middle of its course by a large and conspicuous piliferous pit. 



On the sides of the carapace the pattern is like that of P. cenophorus and 

 P. lagena, the only difference from the latter two species being that in them 

 the bottle-shaped figure is, in the hinder portion of the movable region, 

 carried all across the carapace from side to side. The marginal plates of 

 the movable bands resemble those of Dasyfius, except that they are not 

 so pointed behind. In the anterior part of the carapace they are very 

 small, but become much larger posteriorly. 



The pelvic buckler has been lost from the type and in the other speci- 

 men it has been so much abraded that the markings are obscure, but the 

 pattern does not seem to be materially different from that in P. lagena, 

 and P. cenoplioms. 



Dentition (Plate XIII, fig. 5).- -The teeth are not in a very satisfactory 

 state of preservation. As the anterior part of the rostrum is missing, the 

 dental formula is not determinable, and even in the portion of the jaws 

 which is preserved the small anterior teeth are badly broken. Assuming 

 that the formula is the one usual in this genus, it may be observed that 

 - and - are more quadrate and less pear-shaped than in the allied species, 

 and are much more distinctly divided into two lobes by a vertical, internal 

 groove, while - is relatively larger. 



Upper dentition, length -~- .032. Lower dentition, length 5-ro -33- 



Skull (Plate XIII, figs. 4, 5).- -The skull is large and massive, with 

 full, rounded cranium, the base of which is raised high above the level of 

 the teeth. The occiput is large, both broad and high, somewhat convex 

 transversely and without any prominence for the vermis of the cere- 

 bellum ; near the dorsal summit is a large and deep fossa. The occipital 



