Page:Notes on Osteology of Baptanodon. With a Description of a New Species.pdf/9

Rh Wyoming, and was collected. by Mr. W. Utterback from the marine beds of the Jurassic in 1902. It is now in the collection of the Carnegie Museum.

The large size of all of the vertebræ and the long straight border of the external ends of the coracoids for articulation with the humeri appear to indicate a new species for which I propose the name Baptanodon robustus. Although the material at hand. is insufficient for a satisfactory diagnosis of this form, yet the dimensions of the parts preserved, particularly the vertebræ and ribs, show this to be the largest Member of the Baptanodontidæ. A right coracoid, No. 1953, in the of  shows the same long straight border on the external end and may per-tain to this species.

Vertebræ.— The coalesced atlas and axis are very large, and this is the first indi-vidual I have examined which shows the suture separating these vertebræ. (See Fig. 12, S.) On the lower border the atlas is 35 mm. wide antero-posteriorly, the axis being 30 mm. The great disparity in length antero-posteriorly between the

lower and upper parts of the combined centra appears to be distinctive of this species. The hypapophyses on these vertebræ are very indistinct and no attempt has been made to indicate them in the drawing. (See Fig. 12.) On the third and fourth cervicals the parapophysis appears to be indicated by hardly more than a slight antero-posterior swelling on the side of the centra. In this respect it resembles somewhat the corresponding elements of B. marshi. The succeeding vertebræ have well developed parapophyses on the anterior half of the centra. The diapophyses on all of the vertebræ preserved are very robust and with the articular surfaces on the dorsal surfaces of the centra. The fourth