267 
Relations and Differences. — I know of only one species at all like this 
one, and that is my L. suhconstricta. The ornamentation of both species is 
very similar, hut the last named is much smaller, and its spiral angle is only 
25°, while that of the L. constricta is 29°. 
Dofizon and Localities . — I consider L. constricta one of the most 
characteristic species of the Upper Carboniferous Limestone. I have never 
noticed it in the Middle or Lower Carboniferous Limestone. It is common 
in the Vise Limestone ; it seems rarer in that of Bolland, Yorkshire, near 
Glasgow, Scotland, and at Cork, Ireland. I have also proved its presence at 
Bleiburg, in Carinthia. Mr. Clarke found a single specimen in a dark grey 
limestone on the hanks of the Kama. 
Loxonema acutissima, L. G. de Koninck. 
PI. XXIII, Pig. 22. 
This is a much elongated conical shell, with thirteen or fourteen 
slightly convex spiral whorls with a shallow linear suture. The surface is 
ornamented with a large number of line ribs, scarcely visible to the naked 
eye, and produced by the successive growths of the shell. The shape of the 
aperture is unknown to me. 
Dimensions. — The length is fourteen millimetres ; the transverse 
diameter of the last whorl, four millimetres ; and the spiral angle, 16°. 
Relations and Differences .- — In general form this shell is very like 
that figured hy Phillips, PI. 16, Pig. 23, of his work on Yorkshire, and which 
he has taken for a variety of his Rnecinum {Loxonema) curvilinemn, in spite 
of the great difference between it and the typical species. At present I would 
not venture to affirm that it is the same as this one, hut I know no other species 
at a;ll like it. 
LLorizon and Localities. — This was found with the preceding in the 
limestone on the banks of the Kama, 
2 N 
