/ordan and Evermann. — Fishes of North America. 1027 



Lakes and streams of the south and west from Quebec to Lake Superior 

 and Iowa and south to Mississippi and the Rio (irande, chiefly in swift 

 gravelly streams of some depth, not in brooks; a large darter, readily 

 taking the hook, and abundant in most localities. (/caTrpor, pig ; eI^oc^ 

 resemblance.) 



Srhina raprodes, Rafinesque, Auier. Month. Mag., 1818, .534, Ohio River. 



IWciiia nebiilosa, H.tLDEMAN, Journ. Ac. Nat. Sci. Phila., 1842, 3,30, Susquehanna Piver, 

 Pennsylvania. 



I'ileoma semi/ascinlnni, De K.^y, N. Y. Fauna: Fishes, 16, pi. r,0, fig. 162, 1842, Lake Cham- 

 plain, at Westport, N. Y. 



Perciud himiiaihiiii, IIai.deman, Proc. Bost. Soc. Nat. Hist., 1844, 157, Susquehanna River, 

 Pennsylvania. 



Pileoma carbonaria, Baird & GiRARD, Proc. Ac. Nat. Sci. Phila., 1853, 387, Rio Salado; Rio 

 Medina; San Pedro Creek, Texas. (Type, Nos. 740; 742. Coll. Clark; Keunerly.) 



Asproperca zebra, IIeckel, Canestrini, Verh. Ges. Wien., x, 311, 1860. 



Eiheosloma caprodes, Rafinesque, Ichth. Ohiensis, 38, 1820; Mcenkkaus,* .Vnier. Nat., 1894, 641, 

 pi. 18 and 19. 



Pileotiia Hchulom, Vaillant, Recherches, 51, 1873. 



Pileoma bimaculala, Vaillant, Recherches, 52, 1873. 



Percina cajtrodes, Jordan & Gilbert, Synopsis, 499; Boulenger, Cat. i, .57, and of writers. 



Represented in lakes northward by 



1417a. PEBCINA CAPRODES ZEBRA (Agassiz). 



(Manitou Darter.) 



Head 4i ; depth 7. D. Xy-14; A. II, 10: scales 90. Nape always 

 naked. Lateral black bars short, shorter than in caprodes, not extending 

 much above lateral line ; these also more or less confluent, about 20 in 



* This paper gives an interesting study in specific variations. The following are some of the 

 conclusions reached by Mr. Mcenkhaus in regard to individual variation in Percina caprodes: 



1. The variation between the specimens of a single locality is very slight. 



2. The most complicated color pattern can be connected with the simplest by a series of inter- 

 mediate stages. 



3. The variation in color pattern can not be connected with the latitude inhabited by the 

 different varieties. The color variation is determined, but not in a direct line north and south. 



4. The simplest color pattern of the body, found only in immature specimens, consists of 9 

 transverse bars. 



5. The simplest color pattern of adults, consists of the 9 bars seen in the young plus half bars 

 between each two of the primary bars. 



6. The next complication arises by the addition of iiuarter bars. These bars are first intro- 

 duced in the region between the two dorsals, from which region variation seems to radiate. 



7. Ant)ther complication may be the splitting of the bars into reticulations on the back and 

 their intensification into larger sjiots along the sides. 



8. As to dorsal rays, XV, 15 is the commonest combination, XtV, 16 the next, XV, 16 and 

 XVI, 15 the n(!xt, and so on. The largest percent of any combination does not exct ed 21.052. 



9. The average number of dorsal spines is 15/g, while the number of spines predominating is 

 XV. 



10. The average number of soft dorsal rays is 1'>f^, about the same as the spines— 15 is seen to 

 b<- the number in about 50 per cent of all tlie specimens examined. While 42.11 per cent have 

 XV dorsal spines, and 50.007 per cent have 15 dorsal rays, only 21.05 per cent have a combination 

 of XV spines and 16 rays. 



11. It will be seen that the prevailing numbers of dorsal rays occuring in the more northern 

 streams are XIA', 15. As we go farther south the usual number is XV, 16, and in the most 

 southern streams the numbers are 15, 16, and 17 spines; thespecimens from Texas are peculiarly 

 poor in the number of spines. 



12. The soft rays do not show the same variation found in the dorsal spines, the number being 

 the same for localities north and south. The average number of dorsal spines and rays com- 

 bined oonscqui'Titlv increases with the dorsal spines. 



13. In the anal rays we have, as in the dorsal sjiines, a slight increase in their number from 

 north to south. The'most common number in the Indiana streams is 10, the number increasing 

 to 11 and 12 in the most southern specim'jns. — Moenkhans, I. c. 



