254 EOCENE MOLLUSCA. 
on the edge, and frequently, but not invariably, armed within with three or four 
pliciform teeth ; the sinus is deep, three-cornered, and placed in the margin. 
A variety occurs in which the shell is slenderer, and the spire more pointed. 
Size.—Axis, 6-12ths of an inch; diameter, rather more than 2-12ths of an inch. 
Localities. —Barton, Highcliff, for the type; Bramshaw and Alum Bay (Stratum 
No. 4, Prestwich), for the variety. 
No. 176. Pieurotoma scapriuscuta. Ff. #. Edwards. Tab. XXIX, fig. 2, a—e. 
PievuroToma DeEcussata, Lamk.? 1804. Ann. du Mus., vol. iii, p. 267, No. 25. 
P. testé sub-turritd, tuberculatd, omnino concentrice lineata: spird obtusiusculd, elatd, 
in longitudine dimidium totius teste superanti: anfractibus convewxis, antice coarctatis, 
ad humeros sub-angulatis, unicd serie tuberculorum instructis ; marginibus posticis declivis, 
vie cavatis, granulato-marginatis ; lineis concentricis elevatis, sub-distantibus, simplicibus 
vel leviter denticulatis; apertura obovatd, in canali lato, brevi terminatd ; lobro arcuato, 
acuto, intis plicato ; sinu lato, profundo, sub-trigono, media in margine collocato. 
Var. a, testa tuberculis verticaliter productis, costellas simulantibus. 
Shell turriculated, tuberculated, and ornamented with concentric, raised lines, 
which cover the whole surface: the spire, consisting of six or seven volutions, is 
rather thick and elevated, forming a little more than one half of the entire shell. The 
whorls are convex, slightly contracted in front, and bluntly angulated at the shoulders, 
where they present a single row of small, oblong tubercles, more or less distant in 
different individuals, and crossed by the concentric lines, two of which are generally more 
prominent than the rest ; the posterior margins are moderately wide, gently depressed, 
very slightly concave, and thickened and granulated round the sutural edge. The 
concentric lines are prominent, sharp, and not very distant, varying in this respect in 
different specimens ; they are generally simple and smooth on the edge, but sometimes 
denticulated by the strongly marked lines of growth. The aperture is of a broadish, 
oval shape, and terminates anteriorly in a wide and short, but distinct, canal; the 
outer lip is much arched, sharp-edged, and plicated within ; the sinus is wide, deep, 
somewhat triangular in form, and placed in the middle of the margin. 
A variety occurs, rather plentifully, in which the spire is more pointed, and the 
tubercles on the shoulders of the whorls are lengthened both in front and behind, 
so as to form short, narrow ribs. 
This shell presents so close a resemblance to P. decussata (Lamk.), that I am 
reluctant to consider the two as specifically distinct. The French shell is generally 
narrower, and the body-whorl is less contracted in front and more conical than in the 
English specimens ; and M. Deshayes describes it as being much shorter than the 
spire; but in a series of French specimens, for which I am indebted to the liberality 
