( 385 ) 



Tertiary and more recent molluscs have been found and 

 satisfactorily identified, in considerable numbers, in the 

 vicinity of Truro, as recorded by both Upham and Crosby, 

 and it is perhaps significant in this connection to note that 

 the well-known greensand bed at Marshfield, on the oppo- 

 site shore of Cape Cod Bay, which was originally described 

 bv N. S. Shaler as middle Cretaceous in age,* is now con- 

 sidered by him to be Miocene Tertiary,! apparently without 

 question. 



Although the main object of my search was not attained, it 

 may be of interest to record, incidentally, the discovery, near 

 the lighthouse, of a bowlder of red shale, of Cambrian age, 

 containing numerous trilobite and other remains. My atten- 

 tion was first attracted to it on account of its similarity in su- 

 perficial appearance to the ferruginous nodules of Cretaceous 

 clay, previously mentioned. It was lying in the talus and a 

 single blow with the hammer caused it to break into a num- 

 ber of small pieces. Some of these were submitted to Mr. 

 G. F. Matthew, of the Canadian Geological Survey, to whom 

 I am indebted for the following note. 



(< * * * The fauna is evidently that of the Etcheminian 

 red shale of the Boston basin of Cambrian rocks. The fos- 

 sils are in a good condition of preservation ; the shale is soft, 

 and if you could find the original bed, no doubt a good series 

 of fossils could be obtained." His identifications include the 

 genera Microdiscus, Olenellns, Agraulos, Strenuella and 

 Hyolithcs. 



Other fragments were submitted to Mr. Gilbert Van Ingen, 

 of the New York State Museum, from whose communication 

 in relation to them I quote as follows : 



<< * # * <j\vo of the species are trilobites of lower or mid- 

 dle Cambrian horizons: one is certainly Microdiscus the 

 other appears to be an Olenelhis, but which species I can 

 not yet say. The material is fine and I should like to see the 

 ledge from which the fragment was originally removed." 



*Bull. Geol. Soc. Am. i : 447. 1890. 



t Ann. Rept. U. S. Geog. Surv. 17 : Pt L, 962. 1895-96. 



