Seven new Species of Testacea. 331 
equal size; and it ought, moreover, to be remarked, that the 
latter of these species is most beautifully striated, an appearance — — 
not distinguishable in the other, though perhaps obliterated — + 
chiefly by “the deeper colour and larger size of the spots, which 
show themselves very strongly quite through to the interior of 
the shell; the uppermost line of spots, however, on the gibbous 
part of V. fluminea, is pretty deeply marked. "There are but few 
fluviatile shells in this genus, and the two here described are not 
likely to be confounded with any of them. 
7. Hxrix PLATE. 
Tas. XXIV. Fig. 16, 17. 
Hzrrx testa perforata, subglobosa, levi, alba, lineis transversis 
geminis, apertura interrupto-ovali, labio acutiusculo. 
Habitat in America australi, fluviatilis. 
Testa diametro $ pollicis, solidula, epidermide lutescente, li- 
neis purpurascente-brunneis nunc geminis, nunc solitariis et la- 
tioribus transversim cincta, labio lacteo in columellam apud 
umbilicum replicato. Anfractus 4—5, parum rotundati. Spira 
acuminata. | 
This is a very elegant species; but, as the number of Helices 
contained in Gmelin's edition of the Systema Nature is so large, 
I ought not to pronounce it new with too much confidence. No 
description given by that author, however, can I consider as 
applying to the shell which I have here. named; nor is the latter 
very liable to be confounded with others before known, because 
such of the fluviatile tribe as are elegantly banded are compara- 
tively few. I have -—— its trivial name from the ur. de la 
Plata. 
Before 
