95 



but :i lew. Till' extent (if the variatinii viirii's Ijir^rlv with tiic luiinher of sjieci- 

 mens txaiiiincd ; thai is, the proljability of scriiiiiiii' extremes l>ec<iiiies greater 

 witli ail increase in the luiinher of speeimens eollecti'd. 



The greatest I'Xteiit of variation for anv h)calily as far a- known is tiiroiigli 

 nine rays This has heen found only wiien over scviiily speeimens have been eom- 

 pared. ll decreases to abont live rays with ten speeimens. The total variation 

 for tlie specie's lias not lieen fonnd at any one place. 



The (jiiestion of variation with ele\alion is an int<'restin<i' (me. and may lie 

 taken np in some deiaii. 



In the following lalile((// the localities are grouped according to their average 

 niimlier of ravs : 



Average 



Nuniljcr of 



Ra.vs. 



Nuinher of 

 liOCiilities. 



With Their Klovation.*. 



Li tie Spokane River. ],a30: Griffin Lake, l,i«i: Revelstoke 



on the Coluinhia, 1,475. 

 Lake Washington, 1: Uniitilla River. Pendleton, 1,070; 



Spokane River, 1,910: Colvlle River, Meyers Fat's, 1,200; 



Co'uinbia River, (Jolden, 2,ri50; Grande Ronde River, La 



(irande. 2,7S(); Silver Bow, Brown's (iuleh, .t 344; Pend 



d'Oreille River, Newport, 2,000. 

 Xewaucnm Rivtr, Chehalis, -.04; Natehess River. North 



Yakima, 1,078; Sieanious, l,:i00; Hangman Creek, Spokane, 



1,910; Small Creek, 2,101; Post Creek, 3,100; Flat Head 



Lake. 3.100. 

 Pavette River, 2.ir)ll; Boise River, CaKU ell, 2,372; Skookuni- 



chui-k River. Chehalis, 204. 

 Mission,!; linatilla, .'.OO; Walla Walla River, 326; Potlateh 



Creek. 1,200; Kamloops, 1,158. 

 Clear Wa er Lc«iston, 750: Snake River, Payette, 2,150; 



Colnniliia River, Paseo. .375. 



Tile lowest average, 1"), is I'onnd in Imt three localities, the lowest of whieii is 

 at an elevation of 1.47;") feet. This hist is of no value since only one specimen was 

 <ihtained. iind the elijuu'es are ag:iinst ;in :iver:ige specimen if only one is taken. 



The second average is found all the \v;iy from tide water to an elevation of 

 5.044 feet. It is. however, notidile that only one of the localities. Lake Wash- 

 ington, which does not belong to one of the two hirge water systems, is at a low 

 elevation. The lowest of the other st'ven, :ill of which belong to the Cohnnbian 

 system, is at an elevation of 1,070 feet. 



The third aversige, whiidi is also the gener:il :iverage foi' all the specimens, is 

 found in sevi-n localities, the lowest of which is at an elevation of 204. the highest 

 at 8,100. All l)nt the first, which, again. d(.es not belong to one of the huge river 

 -systems, iire at an elevation above 1,0* feet. 



'J'be fourth :iver:iiie rjinuis from L'04 to 2.:!7'_' feet. 



