﻿Vol. 6l.] OP THE MARINE BANDS IN THE COAL-MEASURES. 533 



of Belgium. Some half-dozen specimens have been found in the 

 marine band below the Gin-Mine Coal at Nettlebank, only one of 

 them being well-preserved. The others, although retaining the 

 spiral ornament, are much distorted by crushing. The shell may 

 be recognized by its small (10 millimetres high), semiglobular form, 

 consisting of five whorls, the last of which composes the greater part 

 of the shell. The smaller whorls appear to be almost in the same 

 plane. The aperture is nearly circular, and the surface is orna- 

 mented with several fine, spiral, linear ridges, which are separated 

 by broader, concave, spiral spaces. 



Locality. — North Staffordshire : below the Gin-Mine Coal. 



NATicorsis brevispira (de Byckholt) 1847. (PL XXXV, fig. 10.) 



Naticodon brevispira, P. de Ryckholt, ' Melanges paleontologiques ' pt. i, 

 1847, p. 78 & pi. iii, figs. 8-9. {Ex Acad. Roy. de Belg. Mem. couronnes, 

 &e. vol. xxiv.) 



Naticopsis brevispira, L. G. de Koninck, Ann. Mus. Roy. d'Hist. Nat. de 

 Belg. vol. vi (1881) p. 22 & pi. i, figs. 23-26. 



I have obtained three small specimens of a shell, which I now 

 refer to Naticojosis brevispira (P. de Eyckholt). They are much 

 dwarfed, the biggest measuring only 7 millimetres in height and 

 8 mm. in breadth. Like the two preceding species, this one has 

 not been previously recorded as occurring in British Carboniferous 

 rocks. It is recognized by its short globose spire of about four 

 whorls, the last occupying by far the major portion of the shell. 

 The aperture is large and oval. There is no decided ornament, and 

 the shell is almost smooth ; but, under the microscope, fine lines 

 and striae of growth may be observed. 



Locality. — North Staffordshire Coalfield: below the Gin-Mine 

 Coal. 



Loxonema acuttjm, de Kon. 1881. (PI. XXXV, fig. 11.) 



Loxonema acutttm, L. G. de Koninck, Ann. Mus. Rov. d'Hist. Nat. de Belg. 

 vol. vi (1881) p. 46 & pi. iv, figs. 34-37. 



It is often very difficult to determine species of this genus, owing 

 to the fact that the shell generally adheres to the matrix, and I 

 have been able to examine only a single example (PI. XXXV, 

 fig. 11) that has the test preserved. Other examples have occurred 

 in the state of casts of the interior, or with the outer layer of shell 

 removed. The peculiar marking is to be seen with the aid of a 

 microscope, and consists of a number of incised curved lines on 

 each whorl, better defined on the upper and more convex portions. 

 Our shell measures only 10 millimetres in height, and its spire 

 consists of about sixteen small convex whorls, the portion of the 

 whorl which envelopes the preceding one having a moniliform 

 ornament. Like the other gasteropoda, this species has not been 

 previously recorded from British Carboniferous rocks. 



Locality. — North-Staffordshire Coalfield: below the Gin-Mine 

 Coal, Nettlebank. 



