268 MEMOIRS OF THE CARNEGIE MUSEUM. 



Tennessee-drainage, which are not well distinguished from it, e. g., E. nebulosa 

 (Conrad). Whether it occurs in the state of New York is doubtful, but it might 

 be found in the upper AUeghenj^-drainage. As the material in the Carnegie 

 Museum shows, it exists in the tributaries of the Ohio in West Virginia. In Ohio 

 it is certainly present, but Sterki (1907a) does not separate the two forms. The 

 form from Lake Erie undoubtedly belongs to novi-eboraci. It ranges practically 

 all over Indiana (Call, 1896a and 1900), and here crosses over into the lake-drainage 

 according to Call. Nevertheless it is quite probable that in northern Indiana its 

 place is taken by the variety; at all events, specimens from Winona Lake in the 

 Carnegie Museum belong to the latter. In Illinois it is reported from the northern 

 half of the state (Baker, 1906), but the common form of the Chicago area is, ac- 

 cording to Baker's description (1898) without doubt the var. novi-eboraci. Still 

 in this region it may pass into the typical form. 



From the foregoing it appears that the typical E. iris belongs to the Ohio- 

 drainage in western Penns.ylvania, West Virgmia, Ohio, Indiana, and possibly 

 Illinois. It may cross over into the lake-drainage, but it seems to be generally 

 represented there by the var. novi-eboraci. Farther to the south it seems to be 

 absent. It has indeed been recorded from the Tennessee-di-ainage, and closely 

 allied forms certainly occur there, but these require further study. A few other 

 records, such as Wisconsin (Simpson), Louisiana and Texas (Baker, 1898) are 

 extremely doubtful. 



Strangely enough, it turns up again in the Ozark region in southern Missouri. 

 Utterback (1916) reports it from the basins of White and Black Rivers, and speci- 

 mens in the Carnegie Museum (James River) are absolutely indistinguishable 

 from Pennsylvanian specimens. 



EuRYNiA (Micromya) IRIS NOVI-EBORACI (Lea) (1838). 

 Simpson, 1914, p. 116, makes this a synonym of Lampsilis iris (Lea). 



Plate XVI, figs. 8, 9. 

 Records from Pennsylvania wanting hitherto. 



Characters of variety: This form differs from the typical E. iris by the color- 

 pattern. The rays are not fine and more or less continuous, but rather broad, 

 distinct, and more or less interrupted and dissolved into dark, almost black, squarish 

 spots. These spots are generally arranged in concentric bands, so that the color- 

 pattern becomes very attractive. 



