STATION IN FRESH-WATER MUSSELS. 295 
2. LEXINGTONIA DOLABELLOIDES CONRADI (Vanatta).—Dia. less 
than 50 per cent. 
Unio maculatus Conrad, ’84 (Elk and Flint R., Ala.).—Pleurobema 
maculatum Simpson, ’14, p. 737. 
Dia. (Simpson) : 46 per cent. : 
Pleurobema appressum Simpson, ’14, p. 747 (Tuscumbia, Ala. ; 
Tennessee and Holston R., Tnnn.). 
Dia. 47 per cent. 
I submit here the following tables: 
Loc. No. Max. Min. Av. 
Tennessee River. 
Rilo nencem Wacvesieracisssets ercie aevelevs.« 4 71 62 67 dolab. 
Biridigie ponte terres a: cc crseietene vest 5 68 54 60 dolab. 
Recart lalla wiry eer « sy reat eds ove in evareon bs. es it 74 74 74 dolab. 
French Broad River, Boyd Creek. 2 61 590 60 dolab. 
Clinch River. 
SOMMER? cages pone cote peace I 50 50 50 dolab. 
(Glhimtonwercrry eer ee eee cites are 4 54 49 2 dolab. (conr.) 
INGRES) a UE ERI oN Cc yeE caer OLTRTERG I 50 50 50 dolab. 
ChinchwRivers Station. sn. .0 se): aa I 44 44 44 conr. 
Clinchporntaewecsc se ce eos Sec ece sree I 42 2 2 conr. 
S tome rail sey ae cxsietecevsimeunleke ai ats eras I 45 45 45 comr. 
@leveland ra taetose no tscersatec 5 40 30 40 conr. 
IRE Sil tee reo COO Com ce eine 6 30 34 36 conr. 
FRuchilatndlWeere cece tecsecns wera cele oe 2 38 36 37 conr. 
(Gietalnp Bibi nae peroccame oc orocece 2 37 36 30.5 cor. 
Similar conditions prevail in Powell River, where no dolabelloides 
have been met with, and where the percentage of conradi drops to 
37 at Big Stone Gap. 
Remarkably enough, I did not find this shell in the Holston 
proper (a case parallel to that of Fusconaia edgariana), but it is 
present again, in the shape of conrad, in North and South Fork 
Holston, and again the law is evident here. This is shown in the 
following table. 
Loc. No. Max. Min. Av. 
South Fork Holston River. 
Bliniii City yea maesyeicasesi ace sucts 4 43 40 41 conr. 
SIT ett mayo sae tharos aco aYerias I 2 42 42 comr. 
[Diino Dena eens es Ae cee ole sae eee I 37 37 37 cor. 
