FAMILY ACERIDA: — BULLA. 15 
This species, which was first detected and described by Col. Totten of the U. S. Engineers 
on the coast of Rhode-Island, and subsequently along the shores of Massachusetts, has also 
been observed on our own coast. ‘Those obtained by Dr. Jay near Rye, at low water on the 
surface of the mud, are much larger than the Rhode-Island specimens, with which, through 
the kindness of Col. Totten, I have been enabled to compare them. Mr. I. Cozzens has 
obtained them from Staten island, below Quarantine ground, in seven or eight feet water ; 
and Dr. Stillman, by dredging in the East river above Corlaer’s hook. These latter were 
olive-green, and covered with a rust-colored epidermis. When a number of these specimens 
are kept in a close vial, they communicate a deep olive-green color to the water. 
Dr. Gould has thought proper to refer the solitaria of Say to this species. 
Buia GOULDII. 
PLATE V. FIG. 101. 
Bulla gouldii. Covurnovy, Bost. Jour. Nat. Hist. Vol. 2, p. 181, pl. 4, fig. 6. 
B: id. Goutp, Invertebrata of Mass. p. 163, fig. 94. 
Description. Shell thin and brittle, small, ovate, convolute ; of four convolutions, rounded 
at their upper edges, and having their sutures well defined, the last whorl with numerous fine 
transverse strie. Spire depressed, discoidal, sometimes slightly mammillated : incremental 
strie very indistinct ; lower extremity rather narrower than the upper. Aperture narrow 
above, and abruptly dilated towards the base by the arcuated inner margin, which is a little 
thickened, white and polished. No umbilicus. 
Color. Shining dead white, with a yellowish epidermis. 
Length, 0°3. Diameter, 0°1. 
This species was first described by Mr. Couthouy, from specimens obtained from the 
stomachs of fishes ; and was subsequently dredged by Col. Totten, in Provincetown harbor, 
Mass. It will probably be found on our coast. Distinguished from insculpta by its flat sum- 
mit, displaying all the whorls. 
Buia OBSTRICTA. 
PLATE V. FIG. 102. Maanirieb. 
Bulla obstricta. Goutp, Am. Jour. Se. Vol. 38, p. 196. 
Bead: Govtp, Invertebrata of Mass. p. 167, fig. 96. 
Description. Shell oval, cylindrical, rather solid, small. Whorls five, the last nearly in- 
volving all the others, pressed in or obstricted at the middle, dilated beneath, and forming a 
fold at the umbilical region. Spire obtuse, rising above the junction of the lip to about one- 
fifth the length of the shell: upper whorls suddenly smaller. Suture deep, apparently double 
in old specimens ; or, rather, a narrow and deep line revolving on the shoulder of each whorl 
