MARYLAND GEOLOGICAL SURVEY 41 



" In the interstices of the specimen portions of matrix remain which 

 have the color and character of the material of the Yorktown forma- 

 tion. Embedded in this at certain points are fragments of Mollusca 

 of the genera Pecten, Lncina and Tnrritella. It was probably derived 

 from the Chesapeake region." Cope, 1896, 



Occurrence. — Chesapeake Group. Probably from Maryland. 



Collection. — Johns Hopkins University. 



Genus CETOTHERIUM Brandt. 



Cetotherium megalophysum Cope. 

 Plate XX, Fig. 1. 



Cetotherium megalophysurn Cope, 1895, Proc. Amer. Philos. Soc, vol. xxxiv, p. 146. 

 Cetotherium megalophysurn Cope, 1896, Proc. Amer. Philos. Soo., vol. xxxv, pp. 143, 

 146, pi. xi, fig. 1. 



Description. — " This species is established on a cranium which is 

 complete from the condyles to near the anterior extremity of the nasal 

 bones inclusive. The apices of the zvgomatic processes of the squa- 

 mosal bones and the left auricular bulla are wanting. The presence 

 of the right bulla in the specimen enables comparisons to be made 

 with species in which this part is preserved and where the cranium is 

 wanting. The skull has lain in the water for a considerable time, as 

 numerous barnacles and oysters have attached themselves to it. The 

 matrix has been generally removed from it by the action of the water. 



" The cranium presents the characters of the genus in the close 

 approximation of the temporal fossae on the middle line and the 

 elongation of the frontals anterior to this point. Portions of premaxil- 

 laries and maxillaries remain at positions much posterior to that of the 

 external nares. The glenoid surface is separated by a sharp angle 

 from the temporal fossa. The sphenoid and presphenoid are keeled on 

 the median line. The vomer is visible between the palatines on the 

 middle line below. 



" The lateral occipital crests form with a line connecting the exoc- 

 cipital processes across the foramen magnum, an isosceles triangle with 

 straight sides, each of Avhich is rather shorter than the base-line men- 

 tioned. The apex of the supraoccipital is not elevated, and is well 



