28 PEOF. T. JEFFEET PAEKEE ON THE 



as the lateral boundary of the foramen magnum and the posterior third of the basis cranii 

 (pp. 9 and 10); they also furnish the supero-lateral facets of the occipital condyle (ox 1 ). 



7. The supraoccipital (s.o) is displaced from its usual position by the union with one 

 another in the middle line of the unusually large epiotis (ep.o) (p. 10). 



8. The prootics (pr.o) are very small, and do not unite with one another below, or 

 help to enclose the canal for the ocular muscles (pp. 10 and 11). 



9. The opisthotics (op.o) are very large and unite with one another mid-ventrally, 

 forming the anterior two thirds of the basis cranii ; each sends off several processes, 

 one of which (op.o 2 ) articulates with the alisphenoid (al.s), and another (o.po i ) forms 

 with its fellow the anterior or double portion of the subcranial crest, the wedge-shaped 

 space between the two forming the canal for the ocular muscles (p. 10). 



10. The sphenotics (sp.o) send off descending processes, which, uniting with ascending 

 processes of the parasphenoid (p.as), form a pair of [postorUtal pillars (p.or.p), immediately 

 in front of the descending processes of the opisthotics (p. 11). 



11. Owing to the union of the large alisphenoid (als) with the opisthotic, the fifth 

 nerve apparently makes its exit, partly in front of the alisphenoid (through the foramen 

 marked A), partly through a foramen (V 3 ) in the opisthotic (pp. 11 and 12). 



12. There are large orbitosphenoids (o.s) uniting with one another in the middle 

 line below, forming a false floor to the anterior part of the brain-case (p. 12). 



13. There is no trace of either basisphenoid or presphenoid. 



14. There is an irregular mesethmoid (m.eth) enclosing a small mesonasal cavity 

 (m.n.c) (p. 12). 



15. The parietals (pa) form faint elevated longitudinal crests on the dorsal surface 

 of the cranium (p. 13). 



16. The frontals (fr) do not unite with one another in the middle line ; they furnish 

 orbital processes (fr 1 ) which roof the orbit ; in front they are produced into large, 

 irregular, pointed processes (p. 13). 



17. The parasphenoid (pa.s) is carried far below the proper level of the basis cranii 

 by the formation of the subcranial crest of which it forms the ventral portion (p. 13). 



18. The vomer (vo) sends off paired ascending processes which clasp the prenasal 

 cartilage laterally (p. 13). 



19. There are distinct, loosely attached nasals (fig. Q,na), bounding the nostril above 



(P- 13). 



20. The suborbital chain is reduced to two preorbital bones (fig. 6, p.or), the anterior 



of which bounds the nostril below (pp. 13 and 14). 



21. The mesopterygoid (fig. 6, 14, and 15, ms.pt) apparently begins as a parostosis, 

 the ossification afterwards extending into the pterygoid cartilage (p. 14). 



22. The premaxillee (fig. 6, p.mx) have large nasal processes (p.mx 1 ) which embrace 

 splint-wise a large laterally compressed cartilage, which works in a median groove of 

 the tegmen cranii and allows for the protrusion and retraction of the jaws (p. 15). 



