OF CONCIIOLOQY. 87 



REPLY TO MR CONRAD'S CRITICISM ON MR. G ABB'S 



"REPORT ON THE PALAEONTOLOGY OP 



CALIFORNIA." 



BY WILLIAM M. GABB. 



The criticisms of Mr. Conrad, in the "Journal of Conchol- 

 ogy " for October, on my paper on Cretaceous Fossils in the 

 "Geological Report of California," and the diametrically oppo- 

 site opinions held by that gentleman and myself, oblige me 

 reluctantly to vindicate my position. 



A reply is rendered the more necessary, from the fact, that 

 the criticism comes from one who is universally acknowledged 

 to be the highest authority on the Tertiary Formations in the 

 country, and who claims that I have described Tertiary fossils 

 as belomnnof to an older formation. 



It would be well to bear in mind the wide difference in the 

 facilities for studying the question in discussion, possessed by 

 Mr. Conrad and myself. A very extensive personal study of 

 the rocks in place, extending over a space of upwards of 

 three years, assisted by suites of many thousands of speci- 

 mens, is hardly to be compared with the examination of a 

 single boulder, even when aided by the carefully digested re- 

 sults of my work. 



I am free to admit, that, when I first saw the newer member 

 of the California Cretaceous, I pronounced.it Eocene Tertiarv, 

 without hesitation. Na} r , more : after I had recognized un- 

 doubted Cretaceous forms in the rock, I still maintained, for 

 more than a year, that there was a mixture of Tertiary forms 

 in it, and it was only after a minute comparison of the doubt- 

 ful species with authentic specimens of Eastern Eocene fossils, 

 that I yielded reluctantly to the conviction, that the rock was 

 unequivocally Cretaceous. An instance of these close rela- 

 tions is found in the resemblance of Architectonica cognata with 

 one of its Eastern congeners. 



But, not to consume more of your valuable space, I shall 



