Oiifiila I.id-c fishes 513 



Habitat. Bean ('03, p. 636) writes that the Miller's Thumb abounds in 

 clear, rocky brooks and lakes, is especially abundant in limestone springs, and enters 

 caves. Hankinsun ('08, p. 216; has found it contined very closely t<j njcky 

 bottoms in Walnut I^'ikc and in nm^t other localities, but in the W'hitefish Point 

 region ( 'lO. ]>. 15J) they were abundant in thick subniergeil masses of ta|)e{jrass 

 and stonewort, in Shelldrake Kiver, where the l>ottom was not stony; a few were 

 also taken on sand aiifl mud Ixjttom. In Lake Superior, however, they were found 

 exclusively in the pebble zone, where they were |)robably common. In Oneida 

 Lake they api)ear to live wholly on rocky lM)ttoms, but we did not determine 

 definitely their distribution. I'mbabiy they are found both in the deep an<l the 

 shallow water of the lake. 



l-ood. ForlK's e.xamined si.x s]>ecimens of Cotttis (very prolably C. hainlii) 

 and reported the foixl to be about 40 per cent aquatic larvae of insects and about 

 25 per cent small fish, the remainder crustaceans of the genus .Isclliis ( P'orbes and 

 Richardson. '09, p. ^^j/ ; Forbes, '83, p. 68; Gill, '08, p. 108). I'earse ('15. p. 

 15) studied the food of ten Cottus ( prolwbly C. bairdii) and found alxjut two- 

 thirds of the food to Ir- insect larvae and the remainder crustaceans (ostrac<Kls, 

 copeiHuls, amphipods. IlyalcUa). midges, leeches, and algae. More recently he 

 ('18, p. 25-) reports on the fcMxl of thirty specimens, with similar results, (ireeley 

 ('27, p. 65) found two s])ecimens of Cottus bairdii taken in the ( ienesee System. 

 X. v., to have fed ui)on May-lly nymphs, midge larvae, filamentous algae and 

 diatoms. Turner ('22, |i. <^5 ) found 25 young Miller's Thumbs (jjrolably Cottus 

 bairdii kumlicni Hoy. since tbi> is the (Ireat l.ake subsiR-cies. according to Hubbs 

 ( 'jft, p. 75), from near l'ut-in-I?ay, < )hio. to have eaten midge larvae and May-fly 

 nymphs principally, but in addition, amphi])ods, fish, beetle larvae, insect eggs, 

 worms, and fil.imentous algae. ILinkinson Cift, p. 152) fomid a large burrow- 

 ing ^L^y-f^y nymph in the cnteron of one sculpin taken in Shelldrake River in the 

 Whitefish I'oint region. The .Sculi>in is also said to devour trout eggs (Jordan 

 and Evcrmann, 'r>8, p. n)?!; Forlies and Richard.son, "09, p. 327). 



Distribution Records. .Ml Cottus found in our six collections from Oneida 

 I^ke were bairdii. Only one s|H'cimen was taken in e.nch collection. The follow- 

 ing collection contained them: Xo. i^). Maple H.iy: No. 40^1, Leete Island: \os. 

 ■\.U. .S35. Xtircross Point; Xo. 441, Taft H.ny; N'o. 4f>o, stream at Cleveland. 



r.iietnies and Pisease. .\ Miller's Thumb was found in the stom.ich of an 

 .\inerican Merganser {.\[er<ius anierieaiius) taken by (". t". .\dan»s and W. E. 

 Sanderson at Cranlterry I-ike, New ^■o^k, .\ugust 21, hm?- Hankinson ('id. p. 

 138) look a Sculpin or Miller's Thiunb two inches long from a Pike {liso.r 

 lueius) six inches long. Wart! Cii. p. 2^/) found 183 ]>arasitic w«)nns in forty 

 specimens examined: twenty tremalodes, one humlred thirty cestodes, .nnd thirty- 

 three nematodes. 



r.ennoinie Relations. The Miller's Thumb is of no value as human I<hmI. 

 In some regions it is tised as Iwit for bl.nck l>ass (Meek ami Clark. '02. p. 1381. 

 It is conunonly considered destructive to tnnit eggs but definite fiHKl studies to 

 fletermine the extent of this injury do not a|ij)car to lie on record. Xo doubt such 

 studies should Ik- made in regions where the s|>ccics is closely ass<x-iatc<l with 

 trout in the s|«wning season. I'ossibly it fee<ls on the eggs of otlier fish also. 



