281 



This lake variety {manitou, Jordan) is one of the most abundant of the fishes 

 in Turkey and Tippecanoe Lakes, and upon it the results given in the following 

 pages are based. 



Six hundred specimens, all that were collected from Turkey Lake, and three 

 hundred of those collected from Tippecanoe Lake, have been examined with a 

 view, first, of making a comparison of this species in the two lakes, and second, 

 of determining the range and character of its variation within Turkey Lake itself. 

 The number of species collected from Tippecanoe Lake is much greater than 300, 

 but this number was thought sufficient to give fairly good results. The effect of 

 natural selection will be taken up at a later time. 



Etheosioma caprodes has two dorsal fins, the first, a spinous one, well separated 

 from the second, which is composed of soft rays. The anal fio is composed of two 

 rather strong spines followed by a number of soft rays. The scales are very reg- 

 ularly arranged, so that they can be definitely counted along the complete lateral 

 lines. The number of spines and rays in these fins, and the number of scales in 

 the lateral line of both sides of the body have been determined. Besides these 

 characters the presence or absence of scales on the nape has been determined. 

 These structures have been taken because, with the exception of the last, they 

 present definite, countable elements, so that in the results the i)ersonal factor is 

 entirely eliminated. 



Curves have been constructed to represent the variation in these structures. 

 In all the curves the horizontal distances represent the countable elements, and 

 the vertical distances the per cent, of specimens possessing these varying elements. 



COMPARISON OF TURKEY LAKE AND TirPECAN(;E SPECIMENS. 



Coloration. — The coloration of these fishes in the two lakes will be taken up 

 in detail later. The color-pattern of Turkey Lake specimens is, on the whole, of 

 a more blotched character than that of Tippecanoe Lake specimens, and shows a 

 slighter affinity to the simple, primitive coloration characteristic of the Wabash 

 Eiver forms. The connection of Tippecanoe Lake with the Wabash River may 

 account for this greater affinity. 



Squamation of Nape. — In Turkey Lake the nape is as a rule naked, while in 

 Tippecanoe Lake it is usually scaled. Table I will bring out the difference. 



