144 PATAGONIAN EXPEDITIONS: PALAEONTOLOGY. 



probably a little too small. Nos. 15,191 and 15,331 are in the Princeton 



museum. 



MEASUREMENTS. 



No. i. No. 15,191. No. 15,331. 



Upper dentition, length 096 .094 



J-, length (*'. e., antero-posterior diameter) 004 



" width (i. e., transverse diameter) 0035 



*, length 007 .007 



" width 005 .005 



i, length OIO .010 .010 



" width 005 .005 .005 



A, length on .0115 



" width .007 .0065 



, length 013 .013 



" width 008 .007 



4, length 014 .013 



" width 008 .0075 



i, length 013 .012 .012 



" width 008 .008 .008 



A, length on .0115 .0115 



" width 007 .007 .008 



No complete skull of this species is known, all of the specimens being 

 incomplete in one or other particular, and the different individuals do not 

 supplement one another in a very satisfactory way. So far as it is pre- 

 served, this skull (Plate XXVIII, figs, i, 2) differs but little from that of 

 Propalceohoplophorus aiistralis ; the occiput is low, broad, erect and nearly 

 plane, or slightly concave, with a more or less prominent vertical ridge 

 for the vermis of the cerebellum ; the occipital crest is of moderate promi- 

 nence and thickness, except on the sides, where it is formed by the periotic 

 and becomes heavy. The basioccipital is broad behind, narrowing an- 

 teriorly ; its ventral surface is nearly flat, except posteriorly, where it is 

 flared to form the margin of the foramen magnum ; between the condyles 

 it is incised by a deep, V-shaped notch. The sagittal crest is quite 

 prominent, rather more so than in the preceding genus, and the zygomatic 

 arch has a reentering angulation on its ventral border, instead of forming 

 one gentle, uninterrupted curve ; in consequence of this, the orbit is rather 

 more oblique ; the lachrymal foramen is somewhat lower in position and 

 nearer to the margin of the orbit ; the incisive foramina are placed a little 

 farther back and the posterior nares notch the palate more deeply. 



