374 



MANUAL OP THE MOLLUSCA. 



eastern low, sandy or muddy, the western rocky, witli deep water near the 

 shore.* 



The comparison of the shells of Eastern and Western America is of con- 

 siderable interest to geologists ; for if is true that any number of living 

 species are common to the Pacific and Atlantic shores, it becomes probable 

 that some portion of the Isthmus of Darien has been submerged since the 

 Eocene Tertiary period. Any opening in this barrier would allow the Equa- 

 torial current to pass through into the Pacific — there would be no more Gulf 

 Stream — and the climate of Britain might from this cause alone, become like 

 that of Newfoundland at the present day. 



XII. Californian Pkoyince. 



The shells of Oregon and California have been collected and described 

 by Mr. Hinds, f Mr. Nuttall;, and Mr. Couthouy, naturalist of the American 

 Exploring Expedition. § 



Shells common to U. California and Sitka. (Middendorff.) 

 Tritonium scabrum. Fissurella aspera. Trochus eui7omphalus. 



Litorina modesta. Trochus ater. Petricola cylindracea. 



,, aspera. „ moestus. Lutraiia maxima. 



Fissurella violacea. „ Fokkesii. 



Scarcely any species are common to this province (extending from Puget 

 Sound to the peninsula) and the Bay of California, which belongs to the 

 Panamic province. The following list probably contains some shells which 

 should be referred to the latter. 

 Fusus "Oreg'onensis. 

 Murex Nuttalli. 

 Monoceros unicarinatus. 



„ punctatus. 



Cancellaria urceoiata. 

 Trivia Californica. 

 Natica lierculea. 



Dentalium politum. 

 Patella, 15 sp. 

 Acmaea scabra. 



„ pintadiua. 

 Chiton Mertensii. 



„ scrobiculatus, .See. 

 Cleodora exacuta. 



,, Lewisii. 

 Calyptrasa fastigiata. 

 Crepidula exuviata. 



„ navicelloides. 



„ solida, &c. 

 Imperator Biischii. 

 Haliotis Cracherodii. 



„ fulgens. 



„ corrugata. 

 Fissurella crenulata. 



,, cacullata. 



Puucturella, 2 sp. 



Waldheimia Californica. 

 Discina Evansii. 



Anomia pemoides. 

 Placuxiomia cepa. 

 Hinnites giganteus. 

 Pema, 1. Pinna, 2. 

 Mytilus, 1, Pecten 2. 

 M\-tilimeria Nuttalli. 

 Modiola capas. 

 Chama exogyra. 



Cardita Tentricosa. 

 Cardium, 4. Lucina, 3. 

 Cypiicardia Californica. 

 Chironia Laperousii. 

 Solecai-dia ebumea. 

 Venus Californiensis. 



,, callosa. 



Aitemis ponderosa 



Saxidomus Petiti. 



„ Nuttalli. 



„ giganteus. 

 Venenipis cordieri. 

 Petricola mii-abilis. 

 Mactra, 2. Donax, 1. 

 Tellina Bodegensis. 



„ secta,&c. 

 Semele decisa. 

 Cumingia californica. 

 Sanguinolaria Nuttalli. 



* Voyage dans I'Amerique IMeridionale. 1 847, t. v. p. v. 

 + Voyge of H. M. S. Sulphur; Zoology by R. B. Hinds, 4to. 1844. 

 X Described byT. A. Conrad, Joiu-n. Acad. N, S. Philadelphia, 1834. 

 § Gould in Host. Nat. Hist. Soc. Proceedings, 1846 ; and U. S. Exploring Exped. 

 (Commander "Wilkes) vol. xii. MoUusca, with Atlas. 4to. Philad. 1852. 



