Grier: a New Rhvnchocephalian. 87 



border of the orbit and the lachrymal bone ha\e taken part in the 

 formation of a cup-shaped depression, (d), which I have not observed 

 in any other species of this genus. Although the left orbit is for the 

 greater part obliterated, the remains of this peculiar depression are 

 well discernible, which would possibly indicate something more than 

 an accidental origin for it. A small wedge-shaped jirojection, pro- 

 truding at right angles from the posterior border of the orbit (e) is 

 evidentl}' the pterj'goid bone in situ. 



The parietals (/) are broad and inclose a small fontanelle. They 

 have been slightly flattened, and compose one-fifth of the greatest 

 breadth of the cranium. Portions of the paroccipital and basisphen- 

 oid bones have been crowded upon them. The temporal arches of the 

 right side of the skull (g) are in position, the constituents showing 

 normally, but the infra-temporal arch appears rather small. On the 

 left side of the skull, the temporal arches are disorganized, and only 

 vestiges of the lower arch are apparent. The quadrate bone is in- 

 visible, but portions of the mastoid may be seen. The skull has 

 become disarticulated from the vertebral column in such a way, as to 

 permit both the occipital condyle and the foramen to be observed (h). 



The Vertebral Column. — Of the cervical vertebrae, the atlas (/) is 

 alone well enough preserved to indicate any peculiarities of structure, 

 appearing as a transverse, arched bar. Well defined impressions of 

 transverse processes are present in the anterior cervical region, and 

 there are at least two pairs of ceivical ribs to be seen. The first five 

 thoracic vertebrae are in fairly good condition, the neural spines being 

 apparently reflexed upon the centra during fossilization, while the 

 transverse processes are missing or indistinct. Various exposed por- 

 tions of the vertebrae indicate their amphicoelous nature. The 

 vertebrae seem to have been quite large, their wddth being one-tenth 

 that of the skull, and their length one-sixth that of the femur. The 

 sacral vertebrae are indistinguishable. 



The greater part of the tail is wanting, the portion which has been 

 preserved consisting of the impressions of seven vertebrae which are 

 characterized by the possession of strong transverse processes, and 

 which have the same numerical relations as the other vertebrae. 

 Intercentra can not be seen throughout the entire length of the 

 vertebral column. The vertebrae in the specimen are as follows: 

 cervicals 6; presacrals 7; sacrals (?); caudals 7. 



Pectoral Girdle and Ribs. — Of the pectoral girdle there are left but 



