GILMORE: OSTEOLOGY OF BAPTANODON (MARSH) 95 
Palatines (pl.). —'The palatines are next in size to the pterygoids of the bones of 
the palate. They are flat plate-like elements that unite posteriorly with the ptery- 
goids and laterally with the pterygoids and vomers. The outer and anterior extent 
of these bones cannot be satisfactorily determined from our specimens. 
Vomers (v.). — These elements are only shown in one specimen, No. 603. Those 
parts interpreted as vomers are two narrow rod-like bones that begin along the outer 
anterior margins of the pterygoids. Anteriorly they follow the outline of the 
skull gradually converging toward one another finally meeting on the median line 
just before they disappear under the premaxille. 
There is no evidence of a bone between the vomer and palatine as shown by 
Frass*' in Ichthyosawrus. 
Mandible.— The mandible appears essentially like that of Ichthyosawrus. It 
consists of five and probably six pairs of bones, the dentary, articular, angular, 
Fria. 1. Cross-section of upper and lower jaws (No. 603), taken at the fracture just above the figure 2 seen in the 
lateral view of the skull, Plate X. Onehalf natural size. ag., angular ; d., dentary ; mz., maxillary ; na., nasal ; pme., 
premaxillary ; pt. ?, pterygoid ; s.ag., surangular ; spl., splenial. rf 
Fia. 2. Cross-section of the lower jaw of the same taken just anterior to the union of the two rami. One half 
natural size. d., dentary ; spl., splenial. 
surangular, splenial and coranoid (?) respectively. The element here called 
splenial is the operculeer of Frass. 
Dentary (d.). —The most anterior and largest of the bones of the lower jaw is the 
dentary. It forms the greater part of the fore portion of the lower mandible. The 
posterior extremity ends under the orbit, its posterior suture running obliquely from 
below the maxillary to a little beyond the posterior end of the symphysis on the 
lower border. The superior side forms the shallow alveolar channel in which the 
teeth are supported. (See figs. 1 and 2.) Posteriorly, the thin inner wall of the 
31 Frass, E., lit, cit., Pl. IL., fig. 2. 
