Cope.] -L4b [May 15, 



45 mm. The external foramina are quite large ; distance between two of 

 them, 165 mm. 



A third cervical vertebra was picked up on the James River, Virginia, 

 by Prof. Bibbins, a few^ miles below the locality from which the type speci- 

 men of the G. crassangultim was derived, and kindl}' presented by him to 

 me. It belongs to an adult animal, and considerable parts of one of the 

 parapophj^ses and neurapophyses are preserved. The former are directed 

 downwards at an angle of about 25°, and therefore much less steeply 

 than in the C. cephalus. The form of the centrum is a transverse parallel- 

 ogram and therefore similar to that of the two individuals previously 

 described. The diameters are : transverse below middle 140 mm. ; ver- 

 tical 97 mm.; anteroposterior at base 84 mm. The dimensions, while less 

 than those of the type C. crassangulum, are appropriate to a smaller in- 

 dividual of that species. 



EXPLANATION OF PLATES. 

 Plate XI. 



Fragmentary crania of Baltenidae of the Yorktown epoch, one-sixth 

 natural size. 



Fig. 1. Cetotherium megnlophysum Cope, from above. ColL .Johns 

 Hopkins University. 



Fig. 2. Cephnlotropis coronatus Cope, from above. Coll. Johns Hop- 

 kins University. 



Fig. 3. Metopocetus durinasus Cope, from above. Coll. Woman's Col- 

 lege, Baltimore. 



Plate XII. 



Diagrams of sections from near the middle of the mandibular rami of 

 extinct BaliEnidiB, one-half natural size. 



Fig. 1. Cetotherium leptocerUruia Cope ; Virginia. 



Fig. 2. Getotherimn cephalus Cope ; Maryland ; section i)ro\imad of the 



middle. 

 Fig. 3. Getotherium cephalus Cope, same jaw as Fig. 2. distad of the 



middle. 

 Fig. 4. Getotherimn davidsonii Cope ; California. 

 Fig. 5. Bhegnopsis paUeatlanticus he'idy ; Virginia. 

 Fig. 6. Mesocetus siphunculus Cope ; Virginia. 



No. 1, Coll. Woman's College, Baltimore; 2, 8, 4. 5. Coll. .\cademy 

 Natural Sciences, Philadelphia ; 6, Coll. E. D. Cope. 



Lettering. 

 So., Supraoccipitalbone ; Sq., Squamosal ; Z., Zygomatic : P.. Parietal ; 

 F., Frontal; N., Nasal; Na., External Nares ; M.v., Maxillary; Pin.r., 

 Premaxillary ; 7'. R., Temporal Kidge. 



