26 FIELD CoOLUMBIAN MusEuM—GEOLOGY, VoL. II. 
Anatomy), is the petrosal of earlier authors, about which there is now 
no discussion. It always articulates behind with the exoccipital and 
paroccipital, above with the supraoccipital, below with the basi- 
sphenoid, and to a greater or less extent with the parietal (in certain 
lizards, etc.), the alisphenoids, when present, and epipterygoids. 
The epipterygoid, the columella of earlier authors, unites the ptery- 
goids with the parietals or frontals. It has been supposed to be 
identical with the alisphenoids by Baur and others, but Baur* later 
retracted this opinion, with reason, as may be seen by an inspection 
of the cranial walls of Sphenodon. 
The alisphenoids (orbitosphenoids of Owen) article with the 
basisphenoid below, when present, and with the petrosals behind. 
In the crocodilia and Sphenodon they also articulate with the epiptery- 
goids. They seem to be absent in the plesiosaurs. 
The bones of the brain capsule in our specimen of Doléchorhyn- 
chops had been separated by maceration before fossilization, and were 
more or less displaced and entangled with one another. Moreover, 
in each temporal vacuity there had lodged deeply a thoracic vertebra, 
wedged in and causing more or less distortion of the temporal arches. 
The atlas and axis, also, were crowded into the occipital region. 
The vertebre had to be sacrificed in order not to endanger the other 
bones. Mr. Martin, with great care and patience, removed the 
disassociated bones of the capsule in more or less completeness, 
They were all soft and mealy, almost of the consistency of brown 
sugar when wetted, but by carefully infiltrating them with a solution 
of gum arabic, the bones were hardened bit by bit and then removed 
from the matrix. This exposed the surface of the basioccipital and 
basisphenoid in their entirety, in an undisturbed and uninjured con- 
dition. A gelatine mould of this surface was then made, from which 
a plaster cast was taken, showing the sutural surfaces for the exoccip- 
itals and petrosals. While none of the bones were obtained quite — 
complete, yet the mates, for the most part, mutually indicate the 
complete characters of each, thus enabling a nearly complete restora- 
tion of the capsule to be made. And the results have been well 
worth all the trouble, as the bones present certain features of much 
interest. 
The brain cavity is broadly open in front, as in the lizards} and © 
Sphenodon, with a broad base on the basisphenoid, a deep depression 

* Zool. Anzeiger, No. 298, 1889. ; 
+ Imthe Pythonomorpha I have recently discovered that the brain-case is bounded in front in: 
part by a well developed orbitosphenoid, uniting the frontal with the basisphenoid, The same bone 
is present in the lizards and snakes. See Bulletin Kans. Univ., 1, No.9, p. 14. ¥ 
