STATION IN FRESH-WATER MUSSELS. 305 
prevail at the upper stations. The metropolis of caperatus is clearly 
in Clinch and Powell Rivers, toward the headwaters. It should be 
noticed that this species does not go very far up in the rivers, and 
that it is by no means a small-creek-form. 
GROUP OF OBOVARIA SUBROTUNDA IN THE UPPER OHIO-DRAINAGE. 
The synonymy of these forms is as follows (see Ortmann, ’18, 
p. 567, 568, but the name Jens has been restored for levigata). 
I, OBOVARIA SUBROTUNDA (Rafinesque).—Dia. 60 per cent. or 
over. 
Obliquaria subrotunda Rafinesque, ’20 (Ohio)—Obovaria subro- 
tunda Vanatta, ’15, p. 552. 
Dias«(Wanatta)) 72" per cent. 
Unio circulus Lea, ’29 (Ohio R., Cincinnati; Monongahela R., Pitts- 
burgh) .—Obovaria circ. Simpson, 14, p. 291. 
Dia (ea): 73) per-cents: (Simpson) : 56,67, 72 per cent.(the 
first given by Simpson falls under the variety !). 
2. Obovaria subrotunda lens (Lea).—Dia. less than 60 per cent. 
Unio Iens Lea, ’31 (Ohio and Tennessee).—Obovaria lens Simp- 
SOU D4: (P1120. 
Dia. (Lea): 48 per cent. ; (Simpson) : 52 per cent. 
The material from the upper Ohio system shows that these two 
forms intergrade completely, as I have pointed out already in 1909, 
and subrotunda is the large-river-form, while lens is found toward 
the headwaters. 
Loc. No. Max. Min. Av. 
Ohio River. 
Borstal where tasrs creo s oyslts asta 12 66 53 62 subr. (lens) 
BR aTcernsh ttroueecpe, ssiie avesies wists ciscnns 2 62 59 60.5 subr. (lens) 
Ste altaya Sea yoann & cisioa vaiees 7 67 SI 62 subr. (lens) 
Coraopolichmems scissile sek ca 5 64 57 61 subr. (lens) 
Monongahela River. 
Chiarlenoieencere een a sree ka aere 5 68 53 60 subr. (lens) 
West Fork River. 
ligne WEES 65 6c6concoodouoosene 4 56 50 53 lens 
HLS catia) Olga a Acasa PSO aes ea 3 49 48 49 lens 
\VGETONG) See A co ail tio So i ea eIa IOS 2 49 45 47 lens 
