ACADEMY OF NATURAL SCIENCES. 305 



the extreme upper limits of the fossiliferous rocks, which are everywhere over- 

 lain by an immense deposit of non-fossiliferous sandstones. Another objection, 

 which has already been raised, that the acknowledged Cretaceous fossils have 

 become mixed with more modern species by the breaking up and re-cementing 

 of an older formation, I shall not even attempt to refute. Had such been the 

 case, I would ere this, in common honesty, have acknowledged it. 



In support of the two conclusions arrived at above, we have the following 

 synopsis of the table : 



Of the 107 species of fossils found in Division B, 44 are found at Clayton, 

 67 at Tejon, 54 at Martinez, 22 at San Diego, 18 near Griswold's, and 7 near 

 New Idria. It is not intended to be understood that these are all of the spe- 

 cies found at these localities ; but that, up to the present time, these are all that 

 have been identified or described. Future work will undoubtedly change the 

 above figures. 



Of the species found at the above localities, 50 are peculiar to one or another 

 locality; 29 are found at two localities only, 14 at three localities, and 14 at 

 four localities or more. 



Taking the three typical localities, Martinez, Clayton and Tejon, 21 species 

 are common to Martinez and Clayton, 30 to Martinez and Tejon, 25 to Clay- 

 ton and Tejon, and 20 are found at all three localities. 



Now, having given what I believe ought to be considered proof conclusive 

 to any candid mind in support of my first proposition, I shall endeavor to 

 establish the second. 



It will be seen that 1G species, found in the upper member, also extend into 

 the older group, Division A. In addition to this, at the locality near Lower Lake 

 Village Lake County, besides several species encountered for the first time, I found 

 15 species in the same bed, within a superficial area of two feet. Of these, 3 were 

 previously known to be common to the upper and lower division. Besides these 

 3, 7 of them were common to this locality, and localities of Division B, and the 

 remaining 5 were, before this discovery, considered peculiar to the lower mem- 

 ber. One of these 5 is found in the Mississippi Valley, in the" Ripley Group," 

 and another belongs to a peculiarly Cretaceous genus. 



As to the species found at the several typical localities, independent of each 

 other, and which would serve to show their individual relations to the older form- 

 ation without corroborative evidence, Clayton has 10 species in common with 

 Division A, Tejon has 7, and Martinez 11. With the Lower Lake bed, Clay- 

 ton has 5 species in common, Tejon 5, and Martinez 6. 



In glancing over Mr. Conrad's "check list," I find that out of the 107 spe- 

 cies found in his " Older Eocene of California," he has only included 74 in his 

 enumeration. He has omitted Callianassa Stimpsonii, Ammonites n. s., Nau- 

 tilus Texanus, Cylichna costata, Mactra Ashburnerii, Cuculkea Mathewsonii, 

 Nucula truncata, and Leda protexta ; eight species, which I mentioned in the 

 Journal of Conchology, (Vol. 2, p. 88) as being found in common in the two 

 members of the Cal. cretaceous, stating distinctly the localities in which they 

 had been found. At the same time he includes five other species, from the same 

 list, in his Eocene catalogue. Whether this be carelessness, or an unfair avoid- 



99 



PROC. ACAD. NAT. SCI. VOL. III. ^^ Jail. 1867. 



