THE OSTEOLOGY OF THE DIADECTIDAE 151 



In. specimen No. 1075 the entire vertebral column is preserved, 

 with the exception of a few terminal caudals. The vertebrae cannot 

 be freed from the hard matrix sufficiently to warrant a complete 

 description, but enough can be seen to show that they conform very 

 closely to the descriptions given above of the other specimens, and 

 that from anterior dorsals to lumbars there is very little change in 

 form. The anterior cervicals are preserved, but the matrix at this 

 point is exceptionally hard and is fissile, so that it has been impossible 

 to make out this important region. A short cervical rib has been 

 uncovered on one side. Although the anterior caudals of this speci- 

 men have not been made out, another specimen in the collection, 

 No. 62, shows the caudal region. This shows that the tail was short, 

 and that the posterior caudals were supplied with strong chevrons 

 pointed sharply backward (Case, 1903; Fig. 10). 



Intercentra are preserved in all parts of the column exposed, i. e., 

 from the cervical to the lumbar. They are thin plates, only slightly 

 curved, so that they extend only a short way up on the sides of the 

 centra. They are broad antero-posteriorly. The intercentra simply 

 underlay the point of contact of two centra and were not closely 

 attached. 



The ribs. — There were evidently ribs on all the vertebrae. The 

 anterior cervicals are covered with matrix, but on one side a rib of 

 about 2 om has been exposed which was attached to either the second 

 or the third cervical. On the third or fourth vertebra the ribs have 

 reached a considerable length, and by the fourth or fifth the ribs 

 have reached the greatest length of the body. As far back as the 

 ninth vertebra the ribs have suffered the distortion described above, 

 so that they are bent sharply backward and upward. In the pos- 

 terior portion of the column the ribs curve sharply to the rear and 

 gradually shorten, so that on the posterior dorsals and the lumbars 

 they are quite short and slender. The dorsal plates overlie the ribs 

 of the anterior vertebrae only. But four plates can be counted in 

 series, but there were probably one or two anterior to them. In the 

 description of specimen No. 62, mentioned above, the author described 

 for the first time the occurrence of the plates in the Diadectidae. In 

 that specimen they occurred as a fragment, but show the presence of 

 at least five. In the anterior plates the ribs seem to be short and fused 



