444 Lake Maxinkuckee, Physical and Biological Survey 



semblance to pores, and which show best when the specimen is 

 somewhat moist. Finally we have the more or less fully devel- 

 oped ctenoid scale, more or less free at the posterior margin and 

 inclined to curl up, which is best seen on the specimen when some- 

 what dry. 



A specimen taken at random from our reserve series had the 

 scales on opercles and cheek 34-19, well developed and ctenoid. 

 The number found in the best developed of our specimens in this 

 respect, out of a series set aside for their special development in 

 this particular, was 23 on the cheek, and 11 on the opercle, from 

 which it varied to 8 on the cheek and 3 on the opercle, and the 

 scales on the cheek are always imbedded and hard to make out. 

 There is no correlation between the number of scales on the cheek 

 and those on the opercle. 



62. AUBEENAUBEE DARTER 



ETHEOSTOMA IOW1E AUBEENAUBEI Evermann 



In making a critical study of the large series of darters which 

 in our preliminary studies were regarded as two distinct species, 

 E. iowse, and E. aubeenaubei, and now greatly augmented by later 

 collections, we find that the two extremes are connected by inter- 

 grading forms. In so far as the squamation of the cheeks, which 

 is one of the most important features, is concerned, they vary 

 from one extreme, the type of E. aubeenaubei, with wholly naked 

 cheeks and opercles, to a form with these parts moderately well 

 scaled ; although none of our specimens seems to be so distinctly or 

 heavily scaled on these parts as the specimens of E. iowse in our 

 reserve series, from Creighton, Neb. 



The typical Etheostoma aubeenaubei differs from typical E. 

 iowse, in the almost naked cheek, the less complete scaling of the 

 opercle, the somewhat longer maxillary, more oblique mouth, the 

 general coloration and much closer approximation of the dorsal 

 fins. 



In a series of 30 specimens examined critically in regard to 

 the points above enumerated, the number of scales on the cheek 

 varies from none to about 15 which could be definitely counted, 

 or, in some examples, to a good many small scales difficult to make 

 out satisfactorily. The scales on the cheek vary from none 

 through 2, 3, 5 to 15 or more, often imbedded and difficult to make 

 out. The squamation appears to proceed from above downward; 

 when these parts were only partly scaled the scales were on the 

 dorsal portion. The length of the maxillary varies from 3 through 



