298 ORTMANN—CORRELATION OF SHAPE AND 
I have also a very interesting series from the Beaver drainage. 
Just below the mouth of Beaver River, in the Ohio at Industry, pure 
catillus is present with the average diameter of 57 per cent. 
Loc. No. Max. Min. Av. 
Beaver River. 
WViatnlpitint nes waees cee etcten taper eee ess 14 61 48 53 cat. (cocc.) 
Mahoning River. 
Moalroningtownhasecimenenctraiclertcier 3 53 40 50 cat. (cocc.) 
GowientSMMr iy a ceotannre saree Hyak ear seers I 50 50 50 cat. 
ILGENAS isa “BooyaodocosodboGne 3 49 46 47 coce. 
NEKO JEAN 98 gandocteeaooucuds I 41 41 41 coce. 
Shenango River (follows Wampum). 
IBleveoyohe. IBsetcloe Aon ooeoeecoddesds B 48 43 46 COGG: 
IEAGUIENS) Fatt eae Otero coke, Steer 5 45 41 43 coce. 
Sharp svillles ees gon comical: I 43 43 43 coce. 
Clarksville ck carson cuciteeectece « 9 52 4I 47 cocc. (cat.) 
SHEMAT On wey racic ooo marae rs 49 42 46 coce. 
WlaTHE STO walt ee ayaci cts one rence Sretereconetele 17 48 37 43 cOcc. 
The elevation of the diameter at Clarksville is due to the pres- 
ence of a number of quite young specimens. We have iearned, 
under the group of Fusconaia subrotunda, that the diameter of 
young shells is comparatively greater. Older individuals at this 
locality are all pure coccineuwm. 
Even in a small creek like the Neshannock, the law becomes 
visible. 
Loc. No. Max. Min. Av. 
Ba SEDO OK: Mec yace oie isie sia lers atorelerhere 8 43 36 4o coce. 
iINeshannock Halls\ 2sanecr oacnoees 3 48 35 41 coce. 
WAGIEATHE pr ae ecg eomerotsn roto mcrae ers 4 42 39 40 coce. 
TRC SSDS he haeaioioheioisls eae aseois See See 4 40 36 38 coce. 
Similar conditions prevail in the Monongahela drainage. At 
Charleroi, the form catillus is rather pure. From farther up I have 
only scanty material, but at the mouth of Cheat River, at Cheat 
Haven, catillus is present (diameter about 50 per cent. or slightly 
more). From the West Fork River I have only specimens of 
typical coccineum, all with the diameter below 50 per cent. 
