8 



MEMOIKS OP THE CARNEGIE MUSEUM 



"The palatine is a small semi-oval bone fitting into the concave anterior border 

 of the pterygoid, and sending forward a slender process for union with the small 

 palatine process of the maxillary. 



"The vomer is a slender triangular bone, united in front by its base to a stout 

 process of the maxillary, which underlaps the ascending process of the premaxil- 

 lary. Along its upper and inner border it unites with the pterygoid, except at the 

 end, where for a short distance it joins a slender process from the palatine. Its 

 lower border is wholly free." 



The Lower Jaws. 



The lower jaws are also wanting in our collections and the following brief de- 

 scription is taken from Marsh, as are also the figures referred to : 



"The lower jaws of Dvplodocus are more slender than in any of the other Sauro- 

 poda. The dentary especially lacks the massive character seen in Morosaurus, and 



Fig. 2. Dentary bone of Diplodocus longus, seen from the left. One third natural size, a, edentulous 

 border ; s, symphysis. After Mai'sh. 



is much less robust than the corresponding bone in B rontosaurus. The short den- 

 tigerous portion in front is decurved (PI. II., Fig. 1), and its greatest depth is at the 

 symphysis, as shown in Fig. 2. The articular, angular and surangular bones are 

 well develoj^ed, but the coronary and splenial appear to be small." 



The Teeth. 



Marsh says, "The dentition of Diplodocus is the weakest seen in any of the known 

 Dinosauria and strongly suggests the possibility that some of the more specialized 

 members of this great group were edentulous. The teeth are entirely confined to 

 the front of the jaws (PL II., Fig. 1), and those in use were inserted in such shallow 

 sockets that they were readily detached. Specimens in the Yale Museum show that 

 entire series of upper and lower teeth could be separated from the bones supporting 

 them without losing their relative position "= "= *," 



