180 A NEW FOSSIL PORPOISE FROM MARYLAND. 



at the tip is much broader, antero-posteriorly, than that of the 3d thoracic. 

 There is a distinct articular facet on the postero-supenor lateral border of the 



Compared with the same vertebra in Phocama the centrum is larger, broader 

 and shorter, and the epiphyses are shield-shaped, rather than rounded. The 

 neural canal is much higher, and the transverse process much narrower, and not 

 produced into a mammillary process at the «rtrmity. A A ,^ ^ 



5th Tlwracic (PI. XX, fig. 4; PL XXI, fig. 4; PL XXII, figs. 4 and 10).-The 

 centrum of this vertebra is much more than one-half as long as broad. The 

 neural spine is erect and tapering, and recurved only at the tip, if at all. Other- 

 wise the vertebra closely resembles the last, but the metapophyses are broader, 

 antero-posteriorly, and the inferior surface of the centrum is rounded, rather 



than flattened. . 



Compared with the same vertebra in Phocama, the centrum is shorter and 



broader the neural spine erected rather than inclined backward, and tapering 

 rather than truncated at the extremity. The transverse process is much nar- 

 rower, and not produced anteriorly at the extremity. 



6th Thoracic (PL XX, fig. 5; PL XXI, fig. 6; PL XXII, figs. 6 and 12).-™* 

 vertebra lacks the neural spine and upper part of the arch. It differs but little 

 from the last, except that the centrum is about as long as broad, that the meta- 

 pophysis has a greater breadth antero-posteriorly. 



7th Tlwracic (PL XX, fig. 6; PL XXI, fig. 5; PL XXII, figs. 5 and U)^ThM 

 vertebra closely resembles the last, but the centrum is longer, and the meta- 

 pophyses are slightly directed upward. The neural spine is somewhat recurved, 

 and the tip distinctly so. The inferior surface of the centrum is somewhat 

 angular. . ., 



This vertebra and the preceding one differ from those of Phocam in tne 

 same manner as does the fifth. In the 7th the neural spine is tapering ana 

 recurved at the extremity, while in PJwccena the extremity is but little narrowed, 



and the posterior edge is nearly straight. # f 



The three vertebrae which follow are probably separated by an interval oi on^ 

 or two from those already described, and are quite defective. The centra are 

 longer than broad, and the epiphyses nearly circular. The inferior surtace 

 the centrum, however, is angular. None of these three vertebrae has facets 

 the articulation of heads of ribs on the postero-superior lateral borders o 



centrum. 



LlTMBABS. 



(PL XX, figs. 10-14; PL XXI, figs. 10-14; PL XXIII, figs. 1-6.) 



Seven lumbar vertebrae are preserved, but all are incomplete, some 

 the neural arch and spine, and others part of the centrum or transverse pro ^ 

 The centra are all longer than broad, and increase rapidly in length as we ^ 

 size from the anterior one backward. They have a very distinct median 



