NEMATOGNATHI 61 



The dorsals of the above specimen have short diapophyses, and might 

 be regarded as posterior, and the anterior might be anticipated to present a 

 different type of articulation with the neurapophyses, as in P. plicatus. But 

 a vertebra of the same size and form but with long diapophyses, from 

 another locality (Upper Green River), presents the same subquadrate 

 articular faces, slightly constricted in the middle. Hence I suspect this 

 character to be characteristic of the species. 



Another specimen is rather smaller than the last. A dorsal vertebra, 

 with inferior diapophyses, is but little wider than deep. The articular 

 surfaces for the neurapophyses are 8-shaped, the areas confluent. A 

 marked peculiarity is seen in the dentary bone. It is much curved in the 

 vertical plane as well as in the horizontal, and must have inclosed a wide 

 mouth. The groove is median, and the inferior and superior surfaces reach 

 it by a nearly equal slope. The former leaves the alveoli without horizontal 

 border, though the latter themselves open on a horizontal plane. There are 

 four and a fraction in .010 m. 



Measurements. 



M. 



Depth of ramus at middlo 013 



Thickness of ramus at middle 006 



Length of posterior dorsal vertebra 006 



Depth of posterior dorsal vertebra 012 



Width of iiosterior dorsal vertebra 013 



From Upper Green River, dedicated to Dr. Joseph Corson, formerly 

 at Fort Bridger, Wyoming, whose researches among the vertebrata of the 

 Bridger basin were attended by rich results. 



NEMATOGNATHI. 



Gill; Cope, Proceedings American Association for the Advancement of Science, 1871, p. 330. 



Parietal and supraoccipital bones confluent. Four anterior vertebrae 

 coossified, and with ossicula auditus. No mesopterygium. Basis cranii and 

 pterotic simple; no coronoid bone. Third superior pharyngeal bone want- 

 ing, or small and resting on the fourth; second directed backwards. One 

 or two pairs of basal branchihyals; two pairs of branchihyals. Suboper- 

 culum wanting; premaxillary forming mouth border above. Interclavicles 

 present. 



