Seven new Species of Tesiacea. 331 



equal size ; and it ought, moreover, to be remarked, tliat the 

 latter of these species is most beautifully striated, an appearance 

 not distinguishable in the other, though perhaps obliterated 

 chieHy 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.Jiuminca, is pretty deeply marked. 'J'here are but few 

 Huviatile shells in this genus, and the two here described are not 

 likely to be confounded with any of them. 



7. Helix Plat;e. 

 Tab. XXIV. Fig. 16, 17. 



Helix testa perforata, subglobosa, Isevi, alba, lineis transversis 

 geminis, apcrtura interrupto-ovali, labio acutiusculo. 



Habitat in America australi, fluviatilis^ 



Testa diametro | pollicis, solidula, epidermide lutescente, li- 

 ncis 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. 



'Jhis is a very elegant species; but, as the number of Helices 

 contained in Gmelin's edition of the Si/stcma NatiircB is so laro-e, 

 1 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 

 veiy liable to be confounded with others before known, because 

 such of the fluviatile tribe as are elegantly banded are compara- 

 tively kw. I have taken its trivial name from the Rio de la 

 Flata. 



Before 



