GILMORE: OSTEOLOGY OF BAPTANODON (MARSH) 83 
the great solidity of the former contrasts strongly with the loose and weak arrange- 
ment seen in the latter. 
The foramen magnum is the largest opening in this view of the skull. It is 
subelliptical in form with the greatest diameter vertical. The opening is bounded 
by the basi-occipital below, exoccipitals and supraoccipital laterally, and supraoc- 
cipital above. There may have been a foramen, see Pl. XI., figs. 1 and 2, between 
the exoccipital, opisthotic, parietal and squamosal, though this cannot be absolutely 
determined from the material at hand. The small elongate opening formed by the 
quadrate and quadratojugal is the “auditory meatus” of Owen. 
The superior view of the skull has the triangular form seen in the lateral aspect. 
Posteriorly on either side of the brain case are the large temporal vacuities sur- 
rounded by the squamosals, parietals, post- and pre-(?) frontals. It will be noticed 
that the sutures between the parietals, frontals and posterior part of the nasals, as 
indicated by the dotted lines are obliterated in these specimens. A pineal foramen 
appears to be present in both of the skulls before me. 
The inferior region posteriorly is well preserved in both skulls but more ante- 
riorly the determination of the different elements has been rendered difficult by the 
crushing to which the specimen was subjected. 
The palate view as shown in PI. IX., fig. 2, has been drawn almost entirely from 
the skull pertaining to specimen (No. 603). 
Medially there is the long interpterygoid vacuity enclosed laterally by the inner 
borders of the pterygoids and posteriorly by the basisphenoid. This vacuity is 
divided posteriorly by the long slender process of the presphenoid. 
Because of the close attachment of the lower jaw the size and extent of the 
pterygomalar vacuity cannot be determined from these skulls. Owing to lateral 
compression the posterior nares have been nearly closed and their exact shape cannot 
be determined. 
MEASUREMENTS OF THE SKULLS. 
No. 878. Greatest length of skull................:..0e-eeseeceesseeeeecsceecerseeeceens 1082 mm. 
“© 603. i oe UD onossnndaodooocouconocao Doo opaGasenoToRAEDOCAnDOdEdeC 1028 ‘* 
“878. GO ake td aly WO: = ie aRscconcaadandndéssedacugoocdooocdesencasoacdaccond ol5iuee 
** 603. ss ce 4 pedadoodaasonedos iodosegogDcobnESte0eeoUsG00R00000000 222 ee 
oo eirteh com height, M255 Sicsestecscvesccuccest-teccese oacnenenes seer er eeeees 320 ‘* 
“ 603. ie ne Fe owccansascaeh cea tacveccessncciesin sta sne Creerecee aces bis} Ot 
Basvoccipital (b.oce.). — The basioccipital is a short heavy bone the most robust 
element of the posterior portion of the skull. It extends backward forming a sub- 
circular convex condyle, which superiorly is separated from the foramen magnum 
by a very narrow nonarticular tract. This tract as it descends is concave and gains 
