STATION IN FRESH-WATER MUSSELS. 285 
Unio flavidus Lea, ’72 (Clinch R., Anderson Co., Tenn.; Holston 
R.; N. Ala.).—Synonym to Pl. tuscumbiensis, according to Simp- 
son) ic 
Dia n(ea)) 52!) per cent. 
I have measured the following material. 
oc; No. Max. Min. Av. 
Tennessee River. 
(Chotage Sino allsigerrse scary etsitaiel=stey- 4 66 51 61 appr. 
Holston River. 
Apleya Minh Aysni5 reiseteveia sre 2 Sac xe I 46 46 46 cun. 
INIGEONn Pome PASE OC OS OOOO oO Oe 10 50 45 51 appr. (cun.) 
llollsitoyan Syevstel gagoodocesuonsoee 2 47 45 46 Cun. 
PATS tiTIMNV ill Womepepeseiee erat cmy st cio econetece 3 54 45 48 cun. (appr.) 
North Fork Holston River. 
Rorthenwoode «ascetics stacdsrs 10 45 390 41 cun. 
TSI Rerae cee Aen matepanten Ch CU OEOT 8 43 36 40 Cun. 
I LesavalGieeh LS ace Bine aa Dae ou eaCR aes 8 46 38 4I cun. 
The general rule, from the Tennessee up the Holston, is seen. 
Irregularities and more sudden changes (from the Tennessee to the 
Holston, and from the latter to the North Fork) may be accounted 
for, on the one hand, by scarcity of material, or, on the other, by the 
sudden transition from a larger river to a smaller one. 
I leave out some material collected in tributaries of the Ten- 
nessee and Holston, because it is fragmentary: but I shouid say 
that it does not conflict with the rule. From the Clinch River, 1 
am able to offer the following table. 
Loc. No. Max. Min. Av. 
Clinch River. 
SGilliena) Be can tecepaunamotone goers I 55 55 55 appr. 
(COMMICTIE SG aac pic OMmeO mane 7 57 47 51 appr. (cun.) 
@TRUGER Boe aiayoe cis sole: sieiateie) Oi eter oa ae I 52 52 2 appr. 
Behe Rope IBOindl cooooosonuoduador 3 45 40 43 cun. 
GlinchiRiversStation .o.4.e se. 6 45 40 43 Cun. 
Opler, Ase bron peuesenocenccece 7 49 39 44 cun. 
Romito Jeol, Socnsocuoecopeoooes I 30 39 30 cun. 
SMEEKSM MERTiya 1 Wievere sioy''s (cle 5'S"S siclere:¢ 9 2 36 40 cun. 
Glin Ch Pore ers eee eevee = oie ecm chansons 6 44 38 41 cun, 
The sudden change of obesity between Offutt and Black Fox 
Ford undoubtedly is due to the fact that a long stretch of the river 
