THE SKULL. 



29 



they give rise to thin, plate-like expansions which are embraced at their posterior end by the pterygoid bones. Dorsally 

 viewed thevomer is seen to become trough-like, the depression being about the width of the shaft of the bone and running 

 the length of the expanded posterior portion. There is no trace of paired elements in the vomer. 



I reproduce here Lull's figure of a palatal view of the skull, showing the vomer in position. 

 I can not agree with Lull's statement that "there is no trace of paired elements in the 



r--R 



Fig. 26. — Palatal view of skull of Triceratops serratus Marsh. Drawn from No. 970, American Museum of Natural History. R, Rostral bone; 

 Nar, narial vacuity; i. pt. s, interpterygoid space: D. g, dental groove; Eus?, Eustachian groove (?); Pmx, premaxillary; Mx, maxillary; 

 Vo, vomer; Pa. s, parasphenoid: Pa?, palatine; Pt, pterygoid. One-ninth natural size. After Lull. 



vomer." As shown in figs. 25 and 27, drawn from the type of Triceratops Tiorridus Marsh, 

 in the posterior portion the vomer shows on its inferior side a distinct median suture, and the 



a While the vomer in the specimen cited is the most perfect known, the portions where indications of pairing would be found if present 

 are so badly cracked as to necessitate repairing with plaster. This repair has effectually concealed any indications of a suture, and while 

 Hatcher is probably correct, Lull's statement concerning the absence of indications of paired condition in this particular specimen is also 

 true. (See fig. 20.)— R. S. L. 



