432 Lake Maxinkuckee, Physical and Biological Survey 



scierus. On a later visit to the same place (October 7, 1907), 

 two large fine darters were secured, one H. aspro, and the other 

 H. scierus. 



The separation of these two species was made with some diffi- 

 culty, and the indications are that they intergrade; this indeed 

 was suggested long ago by Jordan and Gilbert in their description 

 of the subspecies Hadropterus scierus serrula. In nearly all the 

 features in which this subspecies differs from the species to which 

 it is assigned the smaller scales, the naked breast, and relatively 

 weaker serrulations of the opercle it approaches the general type 

 of H. aspro. S<? far as descriptions go it would be difficult to say 

 whether the subspecies in question belonged to aspro or scierus. 

 We have divided our specimens according to the presence or ab- 

 sence of stellate processes along the ventral line. This is a vari- 

 able feature, as these structures differ both in number and degree 

 of development. All other characters separating the species are 

 equally or even more variable. The fishes identified as H. scierus 

 seem in general to have the gill-openings more broadly united, al- 

 though this is not invariably the case. The scales s.eem somewhat 

 more regular along the dorsal line in aspro than in scierus. In 

 scierus there are frequently small rudimentary scales intercalated 

 along the sides of the dorsal fins, breaking up the diagonal series 

 and making it difficult to follow them. This does not appear to 

 be so pronounced in aspro. 



The distinguishing character of the serrulate preopercle is 

 qualified in current 'descriptions by the expression "more or less" 

 and is said to vary with age. Our specimens of scierus vary con- 

 siderably in this respect. None is so distinctly or closely serrulate 

 as in the type; some are almost entire; some rather rough, the 

 roughness being rather crenulate than serrulate, and the preopercle 

 on one side may be considerably more roughened than that of 

 the other side in the same specimen. A pretty constant difference 

 between the species is the presence or absence of scales on the 

 breast; however, one of our specimens which on account of the 

 sum total of other characters we have placed with aspro, has the 

 breast scaled ; the mouths of our specimens average about the same 

 in both species; they may average somewhat larger in our aspro 

 lot ; however, both the largest mouthed and smallest mouthed indi- 

 viduals in the collection belong to those identified as aspro. The 

 dorsal fins are about equally separated in both species, or rather 

 about equally close together there is usually hardly the width of 

 a scale between them ; the two specimens which have these fins far- 

 thest apart belong to the aspro series. 



