140 ON THE COLLECTION AND 



I would strongly recommend that specimens should be 

 procured from various localities, more particularly from the 

 following :-Petersburg, Richmond, Shochoe, Poplin, and Churchill, 

 in Virginia; and from Maryland, Lower Marlborough, New and Old 

 Nottingham, Piscataway, and Rappahannock Cliff. The most 

 prominent forms in this last deposit are — Asterolampra^ Actinop- 

 tyc/ms, Aulacodisais, Adinocychis^ Amphitetras^ Co sino discus ^ 

 Cerataulus^ Dictyocha, Eupodiscus^ Grammatophora^ Heliopeltay 

 Oinphalopelta^ and Melosira, but besides these there are many 

 others, too numerous to mention. In passing, however, I 

 would state for the benefit of those who are anxious to obtain the 

 finest and greatest number of specimens of Heliopelta, that the 

 deposit at Old Nottingham will prove better than any other. For 

 the fresh-water series I would recommend Essex County, Con- 

 necticut River ; Cherryfield, Maine ; Port Hope, Canada ; and 

 Carson City, Nevada. This latter is a deposit which I have 

 just received direct, and is, I believe, but little known ; it is very 

 abundant and pure ; the predominating forms are fine examples of 

 Detiticula laufa, Epithemia ocellata, and Surirella spiralis. In the 

 former stratum Cocconema^ Eunotia, Epithemia, Naviaila, Nitz- 

 schia, Fin?iularia, Stauroneis, and Syjicdra abound in many forms 

 and varieties. 



A stratum similar to the Virginia and Maryland series, but of 

 harder texture, has been found on the Pacific coasts of North and 

 South America, and extending at least from San Francisco to the 

 lower border of California, and, according to Professor Edwards, 

 possibly further in both directions. In the bituminous shales of 

 this series we come to that interesting deposit known as "Monterey 

 Stone," which is well worthy of collection at the points of San 

 Diego and Santa Cruz, because of the fine varieties of Asterolampra 

 which it contains. Monterey stone is usually of a fawn colour, 

 and is distinctly stratified. Large fossil shells and the bitumen 

 of California are found in it. 



At Badjik, near Varna, in Bulgaria, is a stony stratum, having 

 shells and bones mixed with it ; but the Diatomaceas obtained from 

 it are doubtless identical with those contained in our present 

 brackish waters. Speaking from memory, I believe they consist 

 chiefly of some fine examples of Eupodiscus^ but the true deposit 



