284 ORTMANN—CORRELATION OF SHAPE AND 
Loc. No. Max. Min. Av. 
Little Kanawha River, Burnsville. 12 55 40 44 flav. (trig.) 
Raccoon Creek, New Sheffield ... 9 46 42 43 flav. 
Chartiers Creek, Carnegie ....... 3 46 40 44 flav. 
Since the compressed form of the headwaters (flava) very 
gradually passes into the more swollen form of the larger rivers 
(trigona), the distinguishing line between them necessarily must be 
arbitrary. I have adopted 55 per cent. as the limit, so that shells 
with the diameter of 55 per cent. and over are called trigona, while 
shells with less than 55 per cent. are flava. 
GrRoUP OF FUSCONAIA CUNEOLUS IN THE UPPER TENNESSEE- 
SYSTEM. 
Fusconaia flava and trigona are absent in the upper Tennessee- 
drainage, but they are represented there by two allied species, which 
agree in general shape and in anatomy with the Ohio shells, but 
differ from them, and from each other, chiefly in the color of the 
epidermis. They appear to be good species, for they do not run 
into the flava-type anywhere, and I also have never found evidence 
that they run into each other. These shells are F. cuneolus and F. 
edgariana. In both of them, however, the same phenomenon as 
regards obesity is observed. 
F. cuneolus has the following forms and synonyms.™* 
I. FUSCONAIA CUNEOLUS (Lea).—Dia. less than 50 per cent. 
Unio cuneolus Lea, ’40 (Holston R.).—Pleurobema cuneolus Simp- 
Som, 14, p. 743. 
Dia (Lea): 43 per cent.; (Simpson) : 42 and 46 per cent. 
2. FUSCONAIA CUNEOLUS APPRESSA (Lea.)—Dia. 50 per cent. 
or over. 
Unio appressus Lea, ’71 (Tennesse R., Tuscumbia; Holston R.).— 
Pleurobema appressa Simpson, ’0o, p. 749. 
Diae(deea)).: 52 per cent. 
Unio tuscumbiensis Lea, ’71 (Tuscumbia; Holston R.).—Pleuro- 
bema tuscumbiensis Simpson, 14, p. 748. 
Dia. (Lea) : 56 per cent.; (Simpson) : 56 and 58 per cent. 
14 See Pr. Amer. Philos. Soc., 57, 718, pp. 530, 531. 
