﻿Vol. 6t.] the silukian rocks oe llangadock. 575 



three specimens in the Museum of Practical Geology : from the Bone- 

 Bed, Mocktree, from the Aymestry Limestone of Botoyle, Caer 

 Caradoc, and from that of Shucknall Hill, Woolhope, respectively. 

 Also one in the British Museum (Natural History) from the 

 Wenlock Shale of Gaercoed. 



The third variety has a finer keel intercalated between the 

 second and third keels, and four additional fine keels below on the 

 body-whorl. There are two specimens of this in Prof. Groom's 

 collection, and one in the Sedgwick Museum, Cambridge, from the 

 Upper Ludlow Beds, Burton and Brockton. 



The fourth variety is very different from the type. The second 

 and third keels are placed so close together as to give the appearance 

 of a Pleurotomarian band, only the lines of growth pass obliquely 

 over it ; and the base is much flattened, having two additional fine 

 keels and two or three fine threads. There are two specimens of 

 this in Prof. Groom's collection, and one in the Sedgwick Museum 

 greatly resembles it; but it has eight fine keels below instead of two : 

 it is from the Upper Ludlow of Woolhope. 



For the third variety I would suggest the name inter striatum, 

 and for the fourth fas datum; this last differs most from the 

 type, and may possibly prove a distinct species, but interstriatum 

 comes very near the var. glabrum, Lind. 



Dimensions. — The specimen figured in PI. XXXVII, figs. 10 &, 

 11, as possibly resembling the type, has the apex broken ; the four 

 existing whorls have a length of 12*5 millimetres, and the greatest 

 width is 10 mm. 



The variety glabrum, Lindstrom, figured in PI. XXXVII, figs. 12 

 & 13, consists of five whorls in a length of 15 millimetres, and the 

 width is 11 mm. 



The best specimen of the variety interstriatum has only one 

 whorl preserved, and it is not wholly exposed : its height = about 

 7'5 millimetres, and its width = about 8'75 mm. (See PI. XXXVII, 

 fig. 14.) A smaller example has two whorls in a length of 

 6-5 millimetres. 



The biggest example of the variety fasciatum consists of about 

 two whorls, which have a length of 9 millimetres, the greatest 

 width being 12 mm. (See PI. XXXVII, fig. 15.) 



Horizon. — The typical form, as well as the varieties, occurs in 

 (63) the Lower Ludlow, Aymestry Limestone included. The 

 variety glabrum also is found in (90) the Wenlock. 



Etheridge recorded this species as occurring in the Aymestry 

 Limestone, Upper Ludlow, and doubtfully in the Wenlock Shale and 

 Wenlock Limestone. According to Lindstrom, it is found in all the 

 Silurian strata of Gothland. 



Family Tttbbinidjs, Alder. 

 Genus Polyteopina, nov. 



Euomphalus (pars), J. Sowerbj', 1814, 'Mini. Conch.' vol. i, p. 113. 

 Polytropis, L. G. de Koninck, 1881, ' Faune du Calcaire Carbonifere de la 

 Belgique' pt. iii, Ann. Mus. Roj r . d'Hist. Nat. de Belg. vol. vi, p. 107. 



