ACADEMY OF NATURAL SCIENCES. 301 



Donation to the Library : On the Corals and Polyps of Panama, 

 with descriptions of new species, by A. E. Verrill, 8vo. pamphlet. 



Prof. Whitney presented the following communication from Wm. 

 M. Gabb : 



On the Subdivisions of the Cretaceous Formation in California. 



BY WM. M. GABB. 



The recent appearance of a check list published by the Smithsonian Insti- 

 tute, and entitled " Check List of the Invertebrate Fossils of North America — 

 Eocene and Oligocene — by T. A. Conrad," renders it necessary that I should state 

 more clearly than has been done heretofore, the relations between the two mem- 

 bers of the Californian Cretaceous rocks ; and should give all of the proofs that 

 have yet presented themselves, in support of my views. 



In 1856, Mr. Conrad published a paper in Vol. 5, Pacific Railroad Reports, 

 pages 320, et seq., in which he described fifteen shells from the " Eocene " rocks 

 of the Canada de las Uvas, near the present site of Fort Tejon. Of these, 

 eleven were considered by that author as being new to science. The other 

 four were referred to previously described Eocene forms. 



These specimens were procured by Mr. "Wm. P. Blake, geologist of the 

 expedition. They were obtained from a single boulder, the only one found by 

 that gentleman. 



In consideration of the scanty material, it is by no means surprising that Mr. 

 Conrad should have made the determination that he did. The fossils of this 

 locality, and, in fact, of this member of our Californian rocks, have a marked 

 Tertiary aspect. This holds good, both as applied to the appearance of the speci- 

 mens and also to the grouping of the genera. Mr. Conrad's reference of these 

 'fossils to an Eocene age was perfectly justified by the light that he then possessed. 

 Any other paleontologist, with the same specimens, would no doubt have done 

 as he did. But I propose to prove that, after having studied this formation for 

 five years, both in the field and in the closet — both palreontologically and strati- 

 graphically — after having traced it upwards of four hundred miles, and after 

 having collected fossils from it at a dozen localities, I, on the other hand, am 

 perfectly justified in pronouncing it most unequivocally Cretaceous. 



It is, to use a mild term, rather surprising that Mr. Blake, from whom Mr. 

 Conrad obtained his material, should not have collected more specimens- Ac- 

 cording to his report, Mr. Blake reached the depot camp at Tejon, on the third 

 of September, 1853, and did not leave that vicinity until October 10th. Dur- 

 ing that time he traversed the distance between Tejon and the Canada de las 

 Uvas, four times. I am familiar with every foot of the ground on which he 

 camped or on which he travelled ; and I speak from personal observation, when 

 I say that in going from one point to the other he could not avoid passing 

 thousands of boulders and pebbles, full of fossils, similar to the single one sent to 



