GEOLOGICAL SURVEY OF THE TERRITORIES. 417 



Measurements. 



M. 



Length of centrum anterior vertebra 0.021 



Depth of centrum (at middle) anterior vertebra 015 



Width of neural arch at base of spine 010 



Depth of spine 0072 



Length of third vertebra 0135 



Width of neural arch .014 



Width of neural spine 0176 



From a point twenty miles east of Fort Wallace, Kansas. Professor 

 Mudge's collection. 



In this species the vertebra? in question are longer in proportion to 

 their other dimensions than in those described, besides carrying wider 

 neural arches and spines. 



SATJROCEPHALUS PROGNATHUS, (COPE.) 

 (Proc. Amer. PMlos. Soc, Nov., 1870.) 



This species is represented by premaxillary and attached proximal 

 portion of the maxillary bones of the right side, and by a large number 

 of vertebrae and other bones. These portions were associated in the 

 collections placed in my hands by Professor Mudge, and relate to each 

 other in size, as do those of the preceding species and the Ichthyodectes 

 ctenodon. 



The premaxillary is characterized by its great depth as compared with 

 its length, and by the shortness of its union with the maxillary. The 

 palatine condyle of the maxillary reaches a point above the middle of 

 the alveolar margin of the prem axillary. The latter contains alveola? 

 of seven teeth, the anterior of which only presents a perfect crown. 

 This is still more elongate than the crown of the teeth of 8. phlebotomies. 

 It is compressed, equilateral, smooth, and acute. Its direction is even 

 more obliquely forward than the anterior outline of the bone, which 

 itself makes an angle of 50° with the alveolar border. 



The vertebra? consist of cervicals, dorsals, and caudals, to the num- 

 ber of about sixty, most of which are supposed to have been derived 

 from the same animal. The grooves are as in 8. plilebotomus, there being 

 two below, two on each side, and two above. The latter receives the 

 bases of the neurapophyses, which are in many cases preserved. The 

 inferior pair of grooves becomes more widely separated as we approach 

 the cervical series, leaving an inferior plane, which is longitudinally 

 striate-grooved. This plane widens till the grooves bounding it disap- 

 pear. The inferior lateral groove becomes widened into a pit which 

 some of the specimens show to have been occupied by a plug-like para- 

 X)ophysis, as in Mops, &c, or a rib-head of similar form. The neura- 

 pophysial articular grooves become pits anteriorly, and these only of 

 all the grooves, remain on the anterior two vertebra? in the collection. 

 Some of the posterior caudals preserve large portions of the neural 

 arches and spines. They form an oblique zigzag suture with the body, 

 consisting of two right angles, one projecting upward anteriorly, another 

 downward ^behind. The neural spines are very wide and massive and 

 in close contact antero-posteriorly ; these probably support the caudal 

 fin. They are deeply and elegantly grooved from the basis upward. 

 The centra exhibit no lateral grooves. 



An unsymmetrical fin ray accompanied these remains, and from its 

 mineralization, color, size, and sculpture, probably belongs to them. 

 The anterior margin is thinned, and with obtuse denticulations ; the 

 27 G 



