MKi;i;i AM — Till-: tiia i, \ rn is. \ri;i a 9 



( )v('i' a laruc part of the external surface of both niaxiUaries ami [ireinaxil- 

 laries, tlie rostral re<iioii has sciilpfiiri'il into it a series of pits ami ui'ooves. They 

 run lon_i;'itu<liiially on the jireinaxillaries hut have in iicnera] a radial arrange- 

 ment on the maxillaries. They a})pear also on the anterior portion of the lower 

 jaw. While not so strongly impressed as in the ('rocodilia or Stegocephalia they 

 are nevertheless a eharaeteristic feature of the skull in this gi-oup. 



The superior iKin'iil ajxun'tti/ii wvYv situate(l only a short distance in front of 

 the orl)its and are almost immediately ahove the inferior openings. They are 

 separateil l)y a heavy har consisting of the nasals, frontals and premaxillaries. 

 The superior openings are hounded on tlie external side liy the nasals, the pre- 

 maxillaries and apparently to a slight extent hv the maxillaries. Anteriorly 

 they are eloseil hy the premaxillaries. In the type of TJialnttdsaurns there are 

 also present eertain peculiar elements which have somewhat the appearance of 

 anterior prolongations of the prefrontals rising along the anterior margins of the 

 openings. The character of these elements is, however, somewhat doulitful. 



The greater portion of the snout is formed hy thi' pre niaxiUaries, which extend 

 back to form part of the boundaries of the narial openings. The needle-like 

 posterior ends reach hack of the nasals and are thrust between the median ante- 

 rior prolongations of the frontals. In the cross-sections (PI. ii, figs, la, 16 and 

 Ic) the })remaxillaries are seen to be distinctly separated. At section c (PI. ii, 

 fig. Ic) each element shows two large dependent branches, one of which f(_)i'ms 

 the external lateral wall of the snout, the other resting between upward pro- 

 longations of the prevomers. The alveolar margin is set with conical, slightly 

 recurved teeth. The extreme anterior end of the premaxillarv is not known, 

 but judging from the extent to which this bone has narrowed anteriorly, as also 

 from the character of the nearly perfect termination of the lower jaw, only a 

 very small fragment is missing from the type specimen. The dentigerous por- 

 tion of the premaxillarv seems almost to have equaled that of the maxillary 

 in length, though the inferior margin of the maxillary is longer. 



In T. aJe.ra inlnif the posterior end of the inaxiUary is considerably expanded 

 vertically, reaching upward to the lateral prong of the frontal, with which it is 

 folded into the prefrontal (Sec. a. PI. i, fig. 1 and PI. ii, tig. la). The posterior 

 ])art of the alveolar margin is not well preserved an<l it is not known whether it 

 boi-e teeth. No part of this boi-der appears to Ite pitteil or grooved for the 

 reception of teeth. ( )n the antei'ior portion there are two promiiiences which 

 seem to represent fangs from which the crowns have been almost entirely 

 removed. 



In T. pcrri III {\\r maxillary dentition is very well shown excepting on the 

 posterior portion of the jaw, which seems to have been edentulous. The teeth 

 are sharply conical and are set in dee[>, distinct |iits. 



