WILLISTON AND MOODIE : OGMODIRUS MARTINII. 65 



punctiform vascular pits and canals (plate IV, fig. 5), doubtless 

 indicating a rich periosteal blood supply. The articular facttes for 

 the neui'al arches are egg shaped, possessing a length of 31 mm. 

 and a breadth of 15 mm. of the fifteenth vertebra. Between the 

 articular facettes for the neural arch lies the shallow, hourglass- 

 shaped canal for the spinal cord, or rather the meningeal canal. 

 In the center of the canal occur two egg-shaped vascular pits. 

 The centra are slightly constricted in the middle of the bone, 

 although the visceral portion is larger than the neural portion, 

 owing to the presence of the costal articulations. 



The articular siu'faces for the neural spines are identical in the 

 most anterior and in the most posterior. They are oval in shape, 

 with the central point most depressed. Between the depressions 

 for the neural spines superiorly there are two nutrient foramina 

 corresponding in position and undoubtedly in function to the 

 ventral structures of the same. 



The diapophysis stands out moderately; vertically elongate, 

 apparently connected by a narrow surface upward on the arch. 

 The lower extremity of the articular surface, however, reaches 

 pretty well down on the ventrum. 



Transverse diameter of the centrum 84 



Vertical diameter of the centrum 78 



Length 45-48 



The better of the two dorsals is deeply cupped, circular in out- 

 line, with rather sharp rims, rather deeply concave on the sides 

 and below and circular in cross section through middle. Vascular 

 foramen situated high up on the sides, above the middle. 



Length below 55 



Length above 51 



Transverse diameter 100 



Vertical diarrieter 92 



Only a few much water-worn fragments of spinous processes 

 are preserved ■ (plate IV, fig. 3) ; of the neural arch nothing is at 

 hand. One of the best-preserved neural spines is deeply scarred 

 by the teeth of some predaceous Cretaceous fish. The neural 

 spine possesses a height of 85 mm. and a breadth of 31 mm. Out- 

 wardly the spine is smooth, the apex roughened for a cartilaginous 

 tip, apparently indicating an immature animal. 



The neural spines are relatively heavy, broad, and laterally 



flattened. Only fragments of them are preserved, but one of these 



fragments consists of a nearly complete spine. The tip was capped 



by a large amount of cartilage, another indication of the youthful 



5— Sci. Bui. X. 



