A NEW FOSSIL PORPOISE FROM MARYLAND. 181 



carina, with a thin free edge, the outline of which, when viewed from the side 

 is concave, especially in the vertebrae at the posterior end of the series. The 

 under sides of the centrum are concave, and are traversed by very distinct 

 oblique channels. The transverse processes are moderately long, very thin 

 nearly straight, and taper a little at the distal end. They are directed outward 

 with only a slight inclination backward. 



The neural arch and spine are preserved only on one vertebra near the middle 

 of the series. They are nearly vertical, but are slightly inclined backward. 

 The arch is very broad antero-posteriorly, with concave anterior and posterior 

 margins. The spine has a concave anterior border and convex posterior border. 

 It is broader antero-posteriorly than the arch and expanded at the top, which is 

 truncated obliquely, with the angles rounded. The metapophyses are situated 

 a little nearer to the centrum than to the free end of the spine, and are directed 

 obliquely upward and forward. They are irregularly elliptical in outline and 

 thin. There are no distinct anterior or posterior zygapophyses. 



The epiphyses of the lumbar vertebrae are comparatively thin, having a 

 maximum thickness of about 4 mm. 



The lumbars of the fossil form, as compared with those of Phoccena, have 

 more elongated centra, and much broader neural spines, antero-posteriorly, while 

 the metapophyses are larger and are directed obliquely upward, instead of 

 extending horizontally forward. The transverse processes are, however, very 



the two forms 



Caudals. 



(PL XX, figs. 15-19; PI. XXI, figs. 15-19; PL XXIII, figs. 7-11.) 



Only five caudal vertebrae have been preserved. In three of them the trans- 

 verse processes are perforated at the base by a vertical foramen, and, hence, 

 they probably belong near the anterior end of the tail. The sides of the centra 

 both above and below the transverse processes are concave. The postero- 

 inferior facets for the articulation of the chevron bones are very prominent. 

 The neural arch is strongly inclined forward. The spine is not preserved in 

 any of the vertebrae. The transverse process in the most anterior caudal pre- 

 served is about as long as the centrum, quite thin, broad, and nearly straight. 

 It is only slightly inclined backward and is rather expanded than tapering at the 

 extremity, where the free margin is oblique and nearly straight. In one of the 

 vertebrae in which the transverse process is perforated, this process is a little 

 shorter than the centrum, thin, and very broad, with the anterior and posterior 

 margins concave, and the extremity cut off obliquely, so that the anterior margin 

 of the process is much longer than the posterior. The epiphyses of these vertebrae 

 are nearly round, although the centra are distinctly quadrilateral, or irregularly 

 pentagonal. 





