GEOLOGICAL SOCIETY OP PENNSYLVANIA. 



355 



agree in having the transverse apophyses given off on a 

 level (or nearly so) with the basal oi* inferior aspect of 

 the body of the bone, and descending obliquely, so that 

 the distal extremity of these processes is inferior to the 

 base of the bone. All the vertebrae have the inferior 

 aspect of the body marked with one or two blind fora- 

 mina, according to the portions of the column to which 

 they belonged — as in the vertebrae of the Plesiosaurus. 

 PI. 22, fig. 5, represents the transverse processes and a 

 portion of the spinal canal, one half the size of nature. 

 This specimen, like several others, has been fractured 

 transversely in two places, so that one-third anteriorly, 

 and one-third posteriorly, to the transverse process, have 

 been lost. All the large vertebrae display a disposition 

 to fracture at these parts, which arises, doubtless, from 

 the existence of three several points of ossification, divi- 

 ding the bone transversely, previous to ossification, into 

 three separate portions. The present specimen is from 

 the lumbar region, and measures eight inches by nine in 

 diameter ; width of the spinal canal, nearly three inches. 



PI. 24, fig. 1, represents another vertebra of the natu- 

 ral size, and as it presents no mark for the attachment of 

 a rib, must also be referred to the lumbar region ; it is 

 nearly as long again as it is broad, being in total length 

 twelve and a half inches, and not exceeding seven inches 

 in diameter, and is nearly cylindrical, excepting in the 

 vicinity of the processes. The blind foramen is almost 

 obsolete. The spinous process has been elevated, con- 

 torted and fractured, by the pressure of the rock, when 

 forced in whilst in a semi-fluid state, and which now 

 occupies the place of the spinal marrow. 



Bibs. PL 23, Jig, 2. 



The most numerous portion of our collection consists in 

 fragments of ribs, not one of which even approaches to 

 perfection; the spinal extremities, or articulating sur- 



