baenida;. 83 



42 mm. The postfrontal is large, having a length of 32 mm., being in contact by its lower 

 border with the maxilla, the jugal, and the quadratojugal; and by its posterior border with 

 the squamosal. 



The jugal is small, being only 8 mm. in length and 15 mm. in heigth. The squamosal forms 

 the hinder border of the tvmpanic opening. Superiorly it has a thin crest, a relic of the former 

 backward extension of the temporal roof. The tvmpanic chamber extends backward into this 

 bone. The lower border of the zygomatic bar is considerably excavated. Seen from the side the 

 maxilla is convex on its lower border. From this border the bone rises 11 mm. to the orbit. 

 The premaxillae are distinct from the maxilla; and from each other. At the symphysis they are 

 only 3 mm. high, but at the union with the maxillae, 10 mm. high. As in the Bridger species 

 of Baena there are distinct lacrimal bones. The lower border of each comes into contact 

 with the vomer. The jugals are excluded from the rims of the orbits ( Plate 19, fig. 4). 



As seen from below, the maxilla has a broad masticatory surface, its width being 14 mm. 

 from its inner border to the cutting-edge. The inner border of this surface is furnisht by the 

 palatine bone. The latter forms the whole of the outer border of the choana. The masticatory 

 surface does not extend forward on the premaxilla. In front of the choana; there is a deep 

 groove, which in front expands on the lower surface of the premaxillae. There are postpalatine 

 foramina (Plate 21, fig. 2). 



The pterygoids come into short contact with the maxillae. They have distinct ectoptery- 

 goid processes. Where the hinder part of the palate is constricted it is 18 mm. wide. The 

 ptervgoids extend backward to the hinder border of the pedicel of the quadrates, thus sepa- 

 rating the latter widely from the basioccipital and basisphenoid. There is a considerable 

 groove between the quadrate on each side and the median bones of the skull. The pterygoids 

 join in the midline for a considerable distance in front of the basisphenoid. There is on each 

 side ot the latter bone, about the middle of its length, a venous foramen. 



The pedicels of the quadrates are short. The surface for articulation with the mandible 

 is deeply concave from side to side, nearly plane from front to back. 



A pair of epidermal scutes appears to have occupied the space between the anterior 

 halves of the orbits. Behind each of these and bounding the hinder half of the orbit was a 

 smaller scute. A very large scute, or more probably a pair ot them, occupied the area of the 

 frontal bones and overlapt behind this on the parietals. The hinder half of this scute, or 

 these scutes, if two, was separated by two median scutes. The more anterior of these last was 

 circular; the more posterior was broadened backward and lay on the whole or part of the 

 supraoccipital processes ot the parietals. 



Eubaena latifrons sp. nov. 

 Figs. 69, 70. 



The specimen on which the present species is based was found by Mr. Barnum Brown, of 

 the American Museum of Natural History, in Laramie deposits, on Seven Mile Creek, Wyom- 

 ing, about 40 miles northwest of Edgemont, South Dakota. It has the catalog number 6139. 

 The specimen consists of the skull, without the lower jaw. This skull is crusht downward 

 somewhat, and the right maxilla is forced inward partly over the triturating surface of that 

 side. The left maxilla is missing. A part of the temporal roof is broken away and most of 

 the supraoccipital spine is gone. 



It is not impossible that the shell of this species has already been described as one of the 

 Laramie species of Baena; but this can not be determined until the skull and the shell have 

 been found together. The skull resembles that of /s. cephalica; but a number of differences 

 exist, which will be mentioned as the description proceeds. 



How far the premaxillae extended beyond the front of the nasal bones can not be deter- 

 mined exactly; but the distance appears to have been less than in E. cephalica. It may be 

 assumed to have been about 5 mm. The length of the skull, from the front of the nasals to the 

 occipital condyle, is 72 mm. The width from one quadratojugal to the other is ?$ mm. 

 Evidently the orbits looked upward less than in E. cephalica, for the width of the interorbital 

 space is 32 mm.; in E. cephalica, only 25 mm. The horizontal diameter of the orbit is 17 mm., 

 being thus more than in the species with which it is compared. The tympanic chamber, too, 



