278 ORTMANN—CORRELATION OF SHAPE AND 
are connected by intergrades, and any line drawn between them must 
necessarily be artificial and arbitrary. It is advisable, however, to 
retain the old names in a varietal sense, for the extremes are rather 
strikingly different. 
Group oF FUSCONAIA PILARIS IN THE UPPER TENNESSEE- 
DRAINAGE. 
Fusconaia pilaris (Lea) is the representative of FP. subrotunda 
in the upper Tennessee system, and it is extremely hard to distin- 
guish the two. All I can say is that pilaris is a smaller shell than 
subrotunda, a character mentioned also by Simpson. For the rest, 
there is no difference, and it is actually impossible to tell younger 
subrotunda from pilaris, as is shown by the fact that pilaris re- 
peatedly has been reported from the Ohio River. In the Tennessee 
River in northern Alabama, typical swbrotunda is found, and I have 
specimens from this region. But since I have no material from this 
river between these parts and the vicinity of Knoxville, Tenn., I 
cannot discuss the relation of these two forms. They may pass 
into each other. 
The pilaris-group of the upper Tennessee contains a number of 
nominal species which have been distinguished on entirely insuff- 
cient grounds. I have revised them™ in the following way. 
I. FUSCONAIA PILARIS (Lea).—D. 55 per cent. or over. 
Unio pilaris Lea, ’40 (French Broad and Holston).—Quadrula 
pilaris Simpson, ’14, p. 893. 
Dia, (Lea): 63 per cent. Simpson gives two measurements, 
47 and 54 per cent., which, however, belong to the next form, which 
he unites with this. 
Unio globatus Lea, ’71 (Holston) —Quadrula globata Simpson, ’14, 
p. 899. 
Dia. (Lea) : 68 per cent.; (Simpson) : 67 per cent. 
Quadrula andrewse Marsh, ’02 (Holston)—Quadrula andrewsi 
Simpson, 714, p. 895. 
Dia. (Simpson) : 55 per cent. 
11 Proc. Amer. Philos. Soc., 57, 18, pp. 527-520. 
