PROSOBRANCHIATA. 263 
No. 184. Prevroroma sracuEta. F. #. Edwards. Tab. XXIX, figs. 9, a, 4. 
P. testd parva, sub-fusiformi, turritd, longitudinaliter costata, concentrice lineata : 
spira obtusiusculd aperturam in longitudine paullo superanti: anfractibus planulatis, 
ad humeros angulatis, postice concavis, et unicd serie nodulorum munitis; ultimo 
anfractu valde coarctato, in canalem breviusculum producto ; costis numerosis, obliquis, 
angustis, fere ad basin tendentibus ; lineis concentricis sub-distantibus, acutis, irregu- 
laribus: apertura angustd, ovali; labro leviter arcuato, intis prope sinum calloso ; sinu 
lato, brevi, in margine collocato. 
Shell small, fusiform, turreted, longitudinally ribbed, concentrically lined: the 
spire rather thick, and moderately elevated, being a little longer than the aperture : the 
whorls flat-sided, angulated at the shoulders ; the posterior margins narrow, channelled, 
and furnished with a single row of largish round knobs, alternating with the ribs ; 
the last whorl is much contracted in front, and ends in a wide, somewhat short, and 
oblique canal. The longitudinal ribs are moderately thick, rounded on the surface, 
separated by concave spaces as wide as the ribs, oblique, tapering towards the front, 
and extending to the anterior canal; the concentric lines are distant, prominent, and 
thread-like. The aperture is of a narrow, oval shape; the outer lip slightly arched, 
starp on the edge, thickened within near the apex of the sinus, and presenting two 
transverse, oblong callosities, similar to those which characterise P. callifera; the 
sinus is shallow, rounded, and wide, extending over the whole of the posterior 
margin. 
The only specimen I possess has probably not attained its full growth, but it 
presents an union of characters which distinguishes it from all its congeners. It is 
apparently very rare. 
Size.— Axis, 3°5-12ths of an inch; diameter, 1°5-12ths of an inch. 
Locality.— Barton. 
No. 185. Pxrevroroma sinponata. F. #. Eiwards. Tab. XXIX, fig. 12, a, 6. 
P. testé parva, gracil, fusiform, undique spiraliter lineatd, clathratd: spird sub- 
conicad, acuminata: anfractibus convexiusculis, ad humeros sub-carinatis, postice plicatis, 
marginatis; lines spiralibus elevatis, filiformibus, irregularibus, supra margines fere obsoletis ; 
lined unicd humeros cingenti eminentiori, in juventd denticulatd : aperturd ovali, antice in 
canalt indistincto exeunti ; labro leviter arcuato, ad marginem posticam late sinuato. 
A small, slender, fusiform shell, spirally lined, and having an elevated, nearly conical 
and pointed spire, formed of six or seven volutions ; the whorls very slightly convex 
and sharply keeled round the shoulders; the posterior margins wide, sloping gently 
