No.2.] COPE ON MIDCENE RODENTIA. Oil 



maxillary boue in front of the orbit as represented by Filliol in the C. 

 vidacensis. The pterygoid fossa is wide, with the inner process the 

 longer, and reaching the otic bulla. The latter are large and obliquely 

 placed ; the meatal borders are produced into a short tube which is not 

 so long as that of the G. fiber. Its superior border is quite prominent, 

 overhanging the inferior, and projecting more than represented by Mr. 

 Filhol in the G. viciaccnsis. There is a strong ridge of the squamosal 

 bone extending posteriorly from the base of the zygomatic process, 

 whi(;li overhangs a fossa. This fossa is further define I i)osteriorly by 

 the tympanic tube. The fossa is larger and deeper than in either G. fiber 

 or G. vidacensis. Below its superior bounding ridge is a large sub- 

 squamosal foramen. The mastoid bone is distinctly exposed between 

 th(^ squamosal and the occipital, and its surface is separated from that 

 of the former by a groove which is not so well marked in the C. fiber. Its 

 inferior angle is in contact with the bulla, and is shorter than the parocci- 

 ][)ital process. The latter is short, not extending below the line of the 

 condyles, and is directed downwards, not posteriorly as in G. fiber. The 

 occiput is nearly vertical and flat, excepting laterally, where there are 

 two fossne, a superior and inferior, the latter the longer, and extending 

 to the inferior surface. 



The i)remaxillo-maxillary suture is just half way between the anterior 

 molar and the superior incisor, and is vertical to opposite the middle 

 of the incisive foramen, and then turns backwards. The fronto-maxillary 

 and frouto-nasal sutures are in one transverse line across the front. 

 The malar-maxillary suture is behind the anterior border of the zygoma, 

 thus confining the malar bone to the zygoma. The latter is much ex- 

 panded in a vertical direction, but has no postorbital angle, resembling 

 in this respect the G. vidacensis rather than the G. fiber. Its posterior 

 portion extends well posteriorly and below almost all of the squamosal 

 part of the zygoma. The parietal is of a parallelogram mic form ; the 

 anterior inner border cut obliquely by the frontal, and the posterior iuuer 

 border cut out for the supraoccipital. The latter bone has an oval form, 

 narrowed anteriorly and truncate i)Osteriorly. 



I describe a mandibular ramus of a second individual. It unfortu- 

 nately has the coronoid and the angle broken off. The base of the 

 latter is concave on the inner side. The external face of the ramus is 

 everywhere convex. The base of the coronoid is separated from the 

 molar line by a wide groove. The anterior base is opposite the second 

 molar. The incisive alveolus is continued upwards and backwards, and 

 ceases in a protuberance which is external to the plate which connects 

 the condyle with the coronoid process, and is separated from it by a 

 fossa. The condyle is subglobular, and has considerably more external 

 tlian internal articular surface. The series of inferior molar teeth is 

 quite oblique, descending posteriorly. 



Dentition. — The grinding surfaces of the superior molars are none of 

 them longer than wide, and in all but the first the transverse diameter 

 exceeds the antero-posterior. The dimensions diminish posteriorly in all 



