112 



A SYNOPSIS OF THE KECENT AND TEKTIARY FRESHWATER 

 MOLLUSCA OF THE CALIFORNIAN PROVINCE, BASED UPON 

 AN ONTOGENETIC CLASSIFICATION. 



Ey Harold Hannibal. 



Read 8th March, 1912. 

 PLATES V-VIII.i 



GENERAL REMARKS. 



The Califohnian Pkovince. 



The region covered in the following pages has been termed by 

 Woodward, Tryon, Fischer, and Cooke tlie Californian Province. 

 Briefly it embraces the Yukon Easin and tundras to the northward, 

 the entire Pacific drainage of North America from Western Alaska 

 south to the vicinity of San Sebastian Viscaino Bay, Baja California, 

 the Great Basin, and the drainage of the Colorado liiver. This 

 vast area, considered as a whole a well-defined faunal unit, may 

 be conveniently divided into twelve systems,- or faunules, which 

 correspond roughly to the principal drainage areas, viz. : Yulcon, basin 

 of the Yukon River and associated streams flowing into the Arctic 

 Ocean, and tundras to the northward ; Alaska, the Alaska Peninsula, 

 Aleutian Islands, and coastal drainage south to the Stikine Kiver ; 

 Fraser, the Fraser basin, and rivers northward to the Portland Canal, 

 Vancouver and Queen Charlotte Islands, the Puget Sound Region, 

 and tlie streams flowing north and west from the Olympic Peninsula ; 

 Columbia, entire basin of the Columbia lliver, and coastal streams 

 from Gray's Harbour to the Umpqua lliver ; Utah, basin of the extinct 

 Lake Bonneville ; Colorado, the Colorado River and its tributaries 

 above the Needles or thereabouts; Nevada, the drainless basin of old 

 Lake Lahontan ; Klamath, coastal streams from the Rogue to the 

 Redwood River, the Klamath drainage, adjacent desert basins of 

 Eastern Oregon, and streams flowing south from Mount Shasta and 

 westward from the Sierra Nevada Mountains, north of Yosemite 

 Valley; Coast Range, the Sacremento - San Joaquin Valley, southern 

 Sierra Nevada Mountains, coastal drainage from Mad River to 

 Point Conception, and San Francisco Bay region; Mojave, the 

 drainless basins of Owens Valley, Death Valley, Mojave Desert, and 

 the adjacent desert regions of Southern Nevada and South-Eastern 

 California; Los Angeles, coastal drainage from Point Conception to the 

 vicinitv of San Sebastian Viscaino Bay ; Arizona, the Colorado Desert 

 and drainage of the Colorado River below the Needles. 



^ Plates vii and viii will appear in the next part of the ' Proceedings '. 

 - See in this connexion Dall, Pop. Sci. Mo., Ixvi, p. 362, 1905 ; Alaska, xiii, 

 1905, p. 2 ; Hannibal, in West Coast Shells, 1910, p. 229. 



