GAsTEROpoDA. | UPPER PALZOZOIC MOLLUSCA. 547 
Genus. MACROCHILUS (Phiil.) 
Gen. Char.—Shell short, ovate, gibbous, spire rather acute, of moderate length, pointed, of several convex 
whorls; body-whorl large; aperture broad, ovate, rounded in front, pointed behind, indented by the preceding 
whorl; outer lip thin, slightly sinuate in front and oblique; anterior half of columella thickened, flattened : 
posterior half often deficient ; no umbilicus ; surface smooth, or marked by fine, oblique, inversely sigmoidal 
lines of growth. 
These shells strongly resemble the recent Phasianella in almost everything; no trace, however, of the 
great round, stony operculum of the later genus has been found in those rocks which contain Macrochilus 
in abundance. 
Allied to Loxonema, but much shorter, more ventricose, with larger body-whorl, smoother surface and 
wide ovate mouth. 
MACROCHILUS ACUTUS (Sow. Sp.) 
Ref. and Syn.= Buccinum acutum Sow. Min. Con. t. 566. f. 1.=B. imbricatum (not of Sow.) Phill. Geol. 
York. Vol. LI. t. 16. f. 9, 17, 19, 20;2+ B. rectilinewm Phill. ib. f. 10. 
Desc.—Ovato-conic ; apical angle averaging 55°, varying from 50° to 65°; spire acute, of about seven 
slightly convex, gradually increasing whorls ; sutures simple, slightly imbricating ; body-whorl most convex about 
the middle, sloping gradually to the suture, and to the moderately convex elongate base; mouth elongate, 
ovate; anterior half of inner lip only slightly thickened. Surface polished, with nearly obsolete strize of growth 
crossing the whorls with very slight obliquity, having a faint backward curve near the sutures, anda broad slight 
forward curve from them to the base. Length of rather small specimen one inch; proportional average 
width of body-whorl ;;, (varying from ;;, to j;; occasionally), length of body-whorl “, width of penultimate 
whorl , space between last and penultimate sutures = to 3, width of mouth %. 
In the shorter varieties especially, the spire is a little convex when viewed in profile, and in those cases 
the apical angle is measured by tangents to the middle of the penultimate whorl. I think with Prof. Phillips 
that his B. rectilineum is most probably only a variety of this species; but I do not think that the true B. imbri- 
catum of the Devonian limestones of Devon occurs in the mountain-limestone ; the figures given by Phillips, as 
above quoted under that name, belonging clearly to the B. acutwm of Sowerby, and his figures of B, acutum 
belong, I have no doubt, to a different and much more long spired species. M. de Koninck notices one or two 
folds on the columella which I have not yet seen. The extremes of proportional measurements which I 
have given indicate the long and short varieties; the apical angle varies only slightly, owing to the outline of 
the species being convex. 
Position and Locality—Common in the carboniferous limestone of Lowick; not uncommon in the dark 
lower carboniferous limestone of Ronaldsway, Isle of Man; rare in the lower carboniferous limestone of Derby- 
shire ; very common cast in pyrites in the carboniferous shales of Craige, near Kilmarnock. 
MACROCHILUS BREVISPIRATUS (J/*Coy). Pl. 3. H. figs. 7, 8. 
Ref—M°Coy, Ann. Nat. Hist. 2nd Series, Vol. XII. 
Desc.—Elliptical, moderately gibbous, most so about the middle of the length; spire about one-fourth 
of the total length, pointed, of four whorls, gently convex in the middle; sutures slightly imbricating ; 
apical angle varying from 100° to 82°; anterior portion or base produced, moderately convex ; surface smooth, 
with very faint, fine, strie of growth, visible near the mouth, being scarcely sinuous, and very slightly oblique ; 
mouth elongate ovate, indented by the posterior part of body-whorl; anterior half of columella thickened, 
arched. Length of rather small specimen nine lines, proportional length of mouth or last whorl “2, width of 
body-whorl =, width of mouth +, space between last and penultimate sutures +. 
The extreme shortness of the spire separates this from all of the genus at once, except the MW. Michoti- 
anus (de Kon.) ; from that globose species it is distinguished by its much more elongate slender form (indicated 
