1925] 
Storer: A Synopsis of the Amphibia of California 
269 
“ thriving"”; but efforts to obtain specimens in 1924 were unavailing. 
Pipiens is the species of frog used most commonly in physiological 
laboratories, and is also sought commercially for ‘ f rogs-legs ’ ; other 
attempts of planting may therefore have been made within California. 
Life-history . — The habits and life-cycle of this species have been 
described in detail by Dickerson (1906) and Wright (1914). In all 
probability the life-history of the pipiens stock at Alturas and Lake 
Tahoe resembles, in some degree, that of the species in the eastern 
states. In the Colorado Valley, and in the Imperial Valley (where 
this species has probably been carried as a result of the development 
of irrigation), suitable conditions for a marsh-inhabiting frog such 
as pipiens are to be found only along waterways. 
Ruthven (1907, pp. 510-511) states that at Tucson, Arizona, this 
species is to be found only ‘ ‘ about the margins of pools and irrigating 
ditches in the valley of the Santa Cruz River, and along the stream 
in Sabino Canon. It is quite common in these habitats, but is closely 
confined to the vicinity of the water, a fact which limits the migration 
routes of the species in this region to the w T ater courses.” In a foot- 
note this author says that “in the timbered and prairie regions of 
eastern United States this frog is often found a mile or more from 
water, having traveled this distance through damp underbrush or 
long grass. Its migration routes in this region are not, therefore, 
confined to particular streams.” 
Upon a visit to Imperial Valley on March 27 and 28, 1923, the 
present writer found Rama pipiens in some numbers in overflow ponds 
between Brawley and El Centro and in roadside ditches west of the 
latter town between Seeley and Dixieland. In a pool formed at the 
side of the main highway 2 miles east of Dixieland, a mass of eggs 
of this frog was found on March 28, 1923, and there were also ranid 
tadpoles of small size evidently from eggs deposited earlier the same 
month. This particular egg mass was attached to weed stems in the 
water, and was about 75 millimeters (3 inches) in diameter, though 
it was irregular in contour. It was larger than that of Bana b. boylii 
but smaller than that of Bana a. draytonii. Close study showed three 
distinct jelly coats, whereas Wright (1914, p. 17, fig. 1g) figures only 
two coats in material of pipiens collected at Ithaca, New York. The 
embryos in the Imperial Valley material had already begun to 
elongate, so that the size is probably slightly greater than in fresh 
material. Dimensions, in millimeters, were as follows : 
