G38 PROCEEDINGS OE THE NATIOXAL MUSEUM. 



The articular faces look more directly backward aud forward than 

 tbey do in modern snakes with which this specimen has been compared, 

 the difl'ereuce between this species and Python being very marked. 

 The zygapophyses agree with those of raUcopkis in their slight lateral 

 extent, a feature which gives the body of the vertebra a compact, com- 

 pressed appearance, and contrasts with tlie wide spread facets of 

 Python. The facets of the zygospheue look more or less downward, 

 contrasting very strongly with those facets in Python which look 

 obliquely outward, as they do in Pahvophis. The facets of the anterior 

 zygapophyses and zygosphene and those of the posterior zygapophyses 

 and zygautrum lie nearly in j)arallel planes instead of converging, as in 

 Python. 



On each side of the zygantrum, just above the facet, is a foramen 

 communicating with a cavity running well up toward the atiterior 

 zygapophysis, and this in turn communicates with a cavity at the base 

 of the neural spine and one on each side of the body of the vertebra. 

 (See Plates XLV and XLVI.) This feature exaggerates a character 

 found in Python, and other snakes as well, but in Python the foramen 

 is minute and the cavities smaller. 



This species may be provisionally included in the PaIcvo2)hida', 

 although, as we know nothing of the structure of skull of either PaUvo- 

 phis or the present species, the exact relations of both are uncertain. 



This species may not have been marine, although found with Zenylo- 

 don, for a large Emyd was also found associated with it. It does, how- 

 ever, appear probable that it was aquatic. 



The spinous processes are high, as in the semiaquatic Boa and 

 Ancistrodon, but the force of this is weakened by the fact that in the 

 strictly aquatic Pelamys the spinous processes are low. On the other 

 hand, the low point of articulation of the ribs, as in Pelamys, aud the 

 comi)aratively Jiigh compressed character of the vertebra- generally 

 indicate a correspondingly compressed body, such as would be best 

 adapted for swimming. 



From the size of the vertebrie it is evident that the specimen was 

 from 20 to 25 feet in length. 



EXPLANATION OF PLATES. 



Plate XLV. 



Figs. 1-3. Anterior, left lateral, and posterior views of a dorsal vertebra, natural 

 size. 



4. Posterior view of a dorsal vertebra, showing the large foramina on either 



side of the zygantrum, natural size. 



5. Left lateral view of a dorsal vertebra, showing the double hypapophj'sis, 



natural size. 

 Drawn by J. €. McCounell. 



Plate XLVL 



Various views of vertebrte, showing range of size and details of structure, about 

 three-fourths natural size. 



