1846.] Bones of the Zeuglodon. 229 



the processes, as seen in the figure. There appears to be two 

 articulating surfaces at a, the base of the processes- The articu- 

 lating surfaces of the body have a shallow conical depression at 

 the centre, but adjacent to the margin they are slightly convex. 



Rib. — Fig. 4. The shape and structure of the rib is quite re- 

 markable. The bone figured is 2 feet long, but a piece is broken 

 from the sternal portion. Diameter of the articulating surface 

 1^ inches. Transverse diameter of the enlarged part 3^ inches; 

 perpendicular, 2f inches. Fig. 5 exhibits a cross section show- 

 ing the concentric lamina, and the excentric form of the section. 



Large Caudal Vertebra. — Figs. 3 and 4. Form cylindrical, 

 slightly concave in the centre, convex towards their margin. 

 Constricted in the middle with three depressions, c, a. Fig. 4, 

 shows the base of a broad thin transverse process. Lensth of the 

 bone 14 inches. Transverse diameter Sg inches; perpendiculai" 

 7^ inches. The entire length of the transverse process of a lum- 

 bar vertebra is 5 inches. 



Geological position of the Zeuglodon. — In the former account 

 which we gave of the remains of this animal, we stated that they 

 were found in the superior part of the secondary deposits, in beds 

 which might be considered superior to the true chalk. This opinion 

 was founded on the fact that some of the fossils which were asso- 

 ciated with these remains were considered as secondary", — viz., the 

 Authophyllum atlanticum, Phagiostoma dumosum, Nummulites, 

 &,c. ^Ir. Lyell, however, states in a letter to !Mr. B. Silliman, 

 Jr., which is given in a postcript to the March number of the 

 Journal of Science, that the formation is Eocene, or in the oldest 

 of the tertiaiy deposits, 1. I have visited, to use his own words, 

 in the letter referred to, some of the principal localities where the 

 bones of the gigantic Cetacean (the Zeuglodon) have been dis- 

 covered, in Clarke county, Ala., in the fork of the rivers Alabama 

 and Tombeckbee, and find the geological position of the bones to 

 be every where the same, namely, in a white tertiary limestone of 

 the Eocene period, corresponding in ao;e to that of the Santee 

 river, in South Carolina, or of Bucks countv, in Georgia, or that 



