GAsTERopopa. | UPPER PALAZOZOIC MOLLUSCA. 545 
The anterior prolongation of the mouth, and deeply sinuate lip, as well as the apex being simply in the 
line of the other turns, distinguish this Palaeozoic genus from Ohemunitzia. It should be only considered, I think, 
as a subgenus of Macrochilus, as the thread-like strength of the strize and more elongate form are both so 
liable to variation that it is difficult to decide in which of the groups to place several species. 
LoOXONEMA FASCIATA (K7nqg). 
Ref. and Syn.—King, Perm. Foss. t. 16. f. 30; ?+ L. Geinitziana, id. ib. f. 31. 
Desc.—V ery elongate, conic, of ten very gradually increasing whorls, separated by deep simple sutures; 
each whorl strongly convex, most so a little below the middle; apical angle about 25°; surface smooth, or with 
very faint inversely sigmoidal lines of growth under the lens. Length of average specimen four lines, propor- 
tional width 2. ; 
The authentic specimen of this species (received from Prof. King), which I describe, agrees so much more 
precisely with his L. Geinitziana, that I cannot help thinking them the same. The present species receives 
its name from some coloured spiral and transverse bands which I have not seen. 
Position and Locality.—Not uncommon in the Permian limestone of Humbleton. 
LOXONEMA IMPENDENS (J/°Coy). 
Ref—M Coy, Synop. Carb. Foss. t. 3. f. 3. 
Desc.—Very elongate, conic, spire of numerous (about nine or ten) very gradually increasing whorls ; 
apical angle about 23°; surface quite smooth; whorls flat and sloping in the upper three-fourths, tumid, and 
abruptly rounded into the lower suture on the lower fourth ; base moderately convex. Length of last six whorls 
of large specimen (not in the collection) two inches one line, proportional width of body-whorl 4, diameter of 
penultimate-whorl =, space between last and penultimate sutures 34, length of mouth about 4. 
This species differs from LZ. constricta and Lefebvrei in the surface being perfectly smooth, the sutures 
bemg smooth and simple, and not at all constricted or imbricating, as well as the peculiar overhanging 
appearance which the whorls have from the flatness of their upper three-fourths, and the abruptly rounded 
projection of the narrow lower portion beyond the sutures. 
Position and Locality.—Rare in the carboniferous limestone of Derbyshire. 
LoxoNEMA RUGIFERA (Phill.) 
Ref. and Syn.= Melania rugifera Phill. Geol. York. Vol. II. t. 16. f. 26.= Loxonema rugifera 
Phill. Pal. Foss. f. 188. 
Desc.—V ery elongate, spire composed of about thirteen very gradually increasing whorls; apical angle 20°; 
sutures very strongly marked, imbricating, simple; each whorl flattened, and sloping from the upper and 
posterior suture to the lower third, where they are very prominent, and from whence they slope very abruptly 
inwards to the lower or anterior suture ; each whorl crossed by a row of very thick, slightly oblique, longitudinal 
ribs, gradually thickening from the upper suture towards the most prominent lower fourth of each whorl, where 
they abruptly terminate, leaving the narrow lower slope smooth in old specimens, but entirely crossing the 
whorls in young ones ; about fourteen ribs on each of the adult whorls, eleven or twelve on the younger ones, 
separated by slightly larger, deep, concave spaces; body-whorl very little larger than the preceding one, the 
base obscurely concave, produced and smooth; mouth rotundato-quadrate, little longer than wide. 
Length one inch ten lines, proportional width 4, length of mouth or body-whorl =, length of penultimate 
whorl =. 
Position and Locality—Rare in the black beds overlying the main carboniferous limestone of Derbyshire ; 
very rare in the carboniferous limestone of Lowick. 
4a2 
