GasTEROPODA. | UPPER PALAZOZOIC MOLLUSCA. 549 
MACROCHILUS SIGMILINEUS (Phill. Sp.) 
Ref. and Syn. = Buccinum sigmilineum Phill. Geol. York. Vol. II. t. 16. f. 12.+.B. aeutum id. ib. f. 11. (not 
Buccinum acutum of Sow.) 
Desc.—V ery elongate, conic ; apical angle varying from 33° to 40°; number of volutions unknown (six 
commonly preserved), very gradually increasing, each strongly convex, most so below the middle; sutures very 
oblique, deep, simple; width of the penultimate whorl slightly exceeding the length of it and the preceding 
one together; surface highly polished, with faint, sigmoidal strize of growth; base rather abruptly narrowed 
at the front margin. Length of the last six whorls of small specimen one inch (sometimes upwards of three 
inches), proportional length of body-whorl ;%,, space between last and penultimate sutures 5, width of body- 
whorl =, width of penultimate whorl 3. 
This species is easily distinguished from the true MW. acutus of Sowerby, by the great length and slender- 
ness of the spire, more oblique sutures, more convex whorls, &c. The species however figured as Buccinum 
acutum by Phillips, is perfectly identical in all respects; the Macrochilus curvilineus differs in the greater pro- 
portional space between the sutures as compared with the diameter of the whorls, Se. 
Position and Locality.—Rare in the carboniferous limestone of Lowick, Northumberland. 
MacrocHiLus? sprratus (M/‘Coy). Pl. 3. H. figs. 1, 2. 
Ref. and Syn.= Turbo spiratus M°Coy, Synop. Carb. Foss. Irel. t. 5. f. 29. = Natica M°Coyana @Orbigny, 
Prodrome, p. 118. 
Desc.—Elongate, ovato-conic ; spire acute, of five, gradually increasing, moderately convex whorls, each 
of which has a subtabulate or gently concave narrow space just below the sutures, which are simple and im- 
bricating; apical angle 75°; body-whorl moderately convex, base much rounded; mouth ovate, anterior half 
of the thickened inner lip forming a small, sub-semicircular pad, or extension on the body-whorl. Surface 
smooth, with fine obsolete, direct lines of growth. Casts shew a very deep rounded umbilicus, and have 
the sutures strongly channelled and with obtusely rounded edges (the suture of the shell corresponding 
nearly with the middle of the spiral whorls of the cast). Length of rather small specimen eleven lines, 
proportional width =, length of body-whorl or mouth =, width of mouth ;, space between last and penulti- 
mate sutures =. 
This species is distinguished from the M7. acutus (Sow. sp.) by its subtabulate sutures, greater thickness 
of the anterior half of the pillar-lip, &c. 
Position and Locality —Common in the dark carboniferous limestone of Lowick, Northumberland. 
Explanation of Figures.—P\. 3. H. fig. 1, moderate-sized specimen, natural size, partially decorticated ; 
shewing the relative position of the channelled sutures of the cast, and those of the exterior; fig. 2, small speci- 
men with shell perfect, shewing the pad of the umbilicus. 
MACROCHILUS SYMMETRICUS (779). 
Ref. and Syn. = King, Perm. Foss. t. 16. f. 82 and 33, (bad,—whorls too strongly angulated, and body-whorl a 
little too small). 
Desc.—Very elongate, subconic, or hemifusiform, of six very gradually increasing whgrls, separated by 
deeply impressed, simple sutures; diameter of penultimate whorl slightly less than the length of it and the pre- 
ceding one taken together; each whorl very gently convex, most so about, or a little below, the middle; apical 
angle about 33°; base of body-whorl gradually rounded; surface smooth. Length of average specimen five 
and half lines, proportional width of body-whorl %, space between last and penultimate sutures ;;, diameter of 
penultimate whorl =, length of body-whorl =. 
This species is distinguished by its constantly smaller size, &c., from the IZ. ewrvilineus of the carbon- 
iferous limestone, which it much resembles in proportion. 
Position and Locality.—Rare in the Permian limestone of Humbleton. 
