26 Fikld Columbian 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) articulate 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 DolicJiorhyn- 

 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 vertebrae 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 lizardsf and 

 Sphenodon, with a broad base on the basisphenoid, a deep depression 



*Zool. Anzeiger, No. 298, 1889. 



tin the Pythonomorpha I have recently discovered that the brain-case is hounded in front in 

 part hy a well developed orhitosphenoid, 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. 



