44G PROCEEDINGS OF THE ACADEMY OP [1881. 



Bassin de Paris, li, p. 117) it occupies tlie boiizon of the Bracheux 

 sands. The species wherever found appears to be considerably 

 restricted in its vertical range, and its occurrence, therefore, in 

 some of the American deposits would seem to afford some more 

 decided indication of the true age of tliose deposits than could be 

 obtained from the character of the limited number of its con- 

 tained fossils taken as a whole. Associated with Ostrea compres- 

 sirostra were found casts of the large Cucullsea gigantea (Conrad, 

 Journ. Ac. Nat. Sciences, vi, p. 215, 1830;, a species which appears 

 not to be represented in any of the equivalent European forma- 

 tions. But in Virginia, in beds which can be shown to be tlie 

 direct equivalents of those of Maryland, there occurs in addition 

 to the G. gigantea of Conrad, a second species of Cuculleta^ the 

 C, onochela of Rogers (Trans. Am. Philos. Soc, new ser., vi, p. 

 373 ; Latiarca idonea Conr., Proc. Acad. Nat. Sciences, 1872, p. 

 53 — no locality stated), which, if not identical with tlie C. craa- 

 satina of Lamarck, from the Bracheux sands of the Paris basin, 

 is certainly most intimately related to it, and can be considered in 

 every wa}- as its immediate representative,^ It should also be 

 stated that the only other species of Cucullsea described by Des- 

 hayes {Animaux s. Vertehr.^ Bassin de Fai-is, i, p. i09) from the 

 Paris basin ( G. incerta Desh.) is found in the same horizon with 

 the 6'. crassa^ina, and, likewise, the single species described by 

 Searles Wood from the older Tertiaiies of England is a /oicer 

 Eocene form 



If such comparisons are of any value stratigraphically we may 

 fairly look upon the Mar3dand Eocene deposits — the Piscataway 

 sands below, and the Marlborough rock above — as representing a 

 horizon nearly equal to that of the Thanet sands of p]ngland and 

 the Bracheux sands of the Paris basin, or of the British Bognor 



' I have had no specimens of tha European species with which to insti- 

 tute direct comparisons, but as tlie species is a large one, and with well- 

 defined characters, I have relied upon the figures and characters as fur- 

 nished by Daalvc^ye^ {Coquilles Fossile», Enmrons de Paris, i, p. 198 ; Atlas, 

 PL xxxi, tigs. 8 and 9), which are well known for their accuracy. The C. 

 crassatina is catalogued by Prestwich (Quart. Journ. Geol. Soc, 1834, p. 

 109) and Morris ("Cat. Brit. Foss.," p. 197) as being also an English 

 form, and as belonging to the Thanet series, but by Searles Wood ('• Mon- 

 ograph of the Eocene Mollusca " Bivalves, in Pakeont. Soc. Reports, 1861, 

 p. 94), the species occurring at Ilerne Bay, Faversliani, etc., is oousideied 

 to be distinct ( C. decussata Park). 



