FAMILY ACERIDH — BULLA. 17 
Bua TRITICEA. 
PLATE XXXV. FIG. 326. 
Bulla triticea. Coutuovy, Bost. Jour. Nat. Hist. Vol. 2, p. 88, pl. 1, fig. 8. 
B. id. Russet, Essex Jour. Nat. Hist. Vol. 1, p. 75. 
B.id. Govtp, Invertebrata of Mass. p. 165, fig. 98. 
Description. Shell polished, cylindrical, rather solid. Spire slightly depressed, imper- 
forate. Surface traversed longitudinally and transversely by numerous microscopic stria. 
Lip inserted into, or rather arising from, the margin of the circular pit at the summit of the 
spire. Aperture narrow above, almost linear, except at the base, where itis dilated to double 
its previous breadth by the sudden curvature of the columella, which is slightly reflected upon 
the body of the shell. At the region of the umbilicus is a flattened white space, thickened 
by enamel, gradually disappearing within the aperture. The whole inner margin is some- 
times slightly coated with enamel. 
Color. Dull white, covered with a thin shining ferruginous epidermis. Columella white. 
Length, 0°3; diameter, 0°1. 
Neither this shell nor the preceding has been yet found in situ. The present species has 
only been obtained from the maws of fishes on the coast of Massachusetts, but will probably 
be found here. 
Bua DEBILIS. 
PLATE XXXV. FIG. 329, 
Bulla debilis. Goutp, Am. Jour. Sc. Vol. 38, p. 196. 
Bulla debilis. Ip. Invertebrata of Mass. p. 164, fig. 95. 
Description. Shell small, obliquely ovate, tumid, thin and brittle. Whorls four, all rising 
to about the same height; divisions distinct, each very convexly rounded. Last whorl the 
whole length of the shell, including all the others, and partially detached from them above. 
Surface smooth, without any apparent mark. Aperture as long as the shell, widening from 
above. Outer lip attached behind, a little before the summit of the shell, rising to a 
level with the spire, then descending in a regular though slightly waved curve to the front 
of the pillar, where it terminates abruptly. Inner lip spread out into a thin enamel upon the 
body of the shell, partially covering an umbilical indentation placed at about one-fourth the 
length of the shell. 
Color. Greenish white. 
Length, 0°1; diameter, 0°13. 
According to its original describer, this shell has as yet no determinate locality, being 
obtained only from the maws of fish in Massachusetts bay. The same writer suspects that 
it may possibly be the young of B. gouldi, and that it bears a striking resemblance to the 
Fauna — Parr 6. 3 
