AMPULLARIA iasciata, 

 Banded Apple Snail. 



Generic Character. 

 Testa globosa, wnlnUcata. Spira depressa vel breiissima. Apertura 

 i?itegra, magna, oxata. Operculum testaceinn re/ corneum. Animal 

 Jluviatik. 

 Shell globose, umbilicated. Spire depressed or very short. Aper- 

 ture entire, large, oval. Operculum shelly or horny. Animal 

 fluviatile. — Generic Type Helix amjmllacea Lin. 



Specific Character. 

 A. testd oxato-globosd, olivaced, fasciis obscuro-purpureis angustis 



ornatd ; spird brexi, lexatd, apice acuto ; labii margine tenui ; 



umbilico mediocri. 

 Shell ovate globose, olive, with narrow bands of obscure purple ; 



spire short, elevated, the tip acute ; margin of the lip thin ; 



umbilicus moderate. 

 Am. fasciata. En, Meth. pi. 457./. 3. /. 4. (rexersed and young). 

 Helix ampuUacea. Linn. Lister, 130. /•. 30. Seba, t. 38./. 1 to 6, 



58, 59. Chemnitz, 9- 1. 128./. 1135. Gualt. t. 1. R. 



In the selection of generic characters, sufficiently important 

 to separate Ampullaria from Paludina, great difficulty at 

 present exists ; as the fundamental principle on which they 

 should be founded (the formation of the animal) is entirely 

 wanting. It is only known that these shells, like the Palu- 

 dinae, are furnished with an operculum. The absence or 

 presence of this organ has been found of the first generic 

 importance ; though the substance of which it is composed, 

 as well as the form it assumes, can be considered only as 

 indicating specific distinctions. This is proved from the 

 fact, that among the Naticse some have horny, and some 

 shelly, opercula : in Phasianella, this partis, in some species, 

 almost flat, in others remarkably convex; in Turbo, Lam. its 

 form is even more variable, and in the present genus a similar 

 uncertainty exists. One species alone has been positively 

 described as having this part shelly, while in two others the 

 operculum is as certainly known to be horny ; to these last 

 may be added a third, found by myself in the lakes of 

 Pernambuco in Brazil, but to which I have not immediate 

 access. The shells here figured were, however, received from 

 the same place by Mrs. Mawe, and, I think, are of the 

 identical species. The spire is sometimes worn, and the 

 whole shell very thin. 



Several fossil shells of this genus are mentioned as ex- 

 isting in the extinct volcanoes of Ronca, in bituminous marl 

 near'Pont St. Esprit, &c. as quoted (on the authority of the 

 illustrious Cuvier) by Mr. Bowdich. 



PI. 103. 



