16 NEW-YORK FAUNA — MOLLUSCA. 



near the suture, forms a channel. Aperture narrow above, enlarged beneath. Outer lip 

 sharp, entire, joining the preceding whorl by a gradual approach, and then turning down the 

 inner border in the form of a thick slightly attached plate of enamel : As it turns back from 

 the front, it becomes thicker and rounded, and at the umbilical region it enters the shell, and 

 forms a conspicuous fold. 



Color. Whitish or pale horn-color, with a thin ferruginous epidermis. 



Length, 0-1 -0-2; diameter 0-07 -0-1. 



Found in the stomachs of fishes on the shores of Massachusetts, and by dredging in the 

 harbor of New- York below the Quarantine ground. The presence of a prominent spire in 

 this and a few other species, with a fold on the columella, would seem to indicate the neces- 

 sity for a subgeneric division. The characters assigned by Lamarck, " n'ayant point de 

 columelle ni de saillie a la spire," certainly require revision. The B. canaliculata of Say, 

 which belongs to this division, is referred by that author to Bullina of Ferussac, on account 

 of the animal having two distinct tentacula ; but this would necessarily remove it from the 

 present family. I am not aware that Deshayes, who says that the animals of the two genera 

 agree exactly, has had an opportunity of examining Mr. Say's species. I scarcely know 

 what to make of another species described by Mr. Say as a Bulla, under the name of B. 

 fluviatilis (Journ. Acad. Vol. 2, p. 178), inhabiting fresh water. All the known species are 

 marine. It may possibly prove to be what I have ventured to describe under the name of 

 Physa planorbula. 



Bulla lineolata. 



PLATE 35 FIG. 334. 



Bulla lineolata. Couthouy, Bost. Joam. Nat. Hist. Vol. 2, p. 179, pi. 3, fig. 15. 



IS. id. Coni.n, Invertcbrata of Mass. p. 169, fig. 99. 



Description. Shell very small, oblong-ovate, broadest at the base, thin and fragile. Whorls 

 three ; the last inflated, and enveloping all the others, with numerous impressed minute revolv- 

 ing striag. Spire little, prominent, flattened, with the outer lip arising from near its summit. 

 Aperture the whole length of the shell, narrow above, dilated beneath, somewhat effuse at the 

 base ; a faint oblique fold near the middle of the columella. 



Color. Pale brown, with a thin ferruginous epidermis ; within, glossy yellowish white. 



Length, 0*15; diameter, • 07. 



This very delicate and minute shell has as yet only been observed by its original describer, 

 in the stomachs of haddocks and other fishes on the northern coast. 



