﻿Vol. 6 1.] SILUEIAN GASTEEOPODA FEOM LLANGADOCK. 



567 



27. On some Gasteropoda from the Silurian Rocks of Llangadock 

 (Caermaethenshiee). By Miss Jane Donald. (Communicated 

 by Prof. Theodore Groom, M.A.,D.Sc.,F.G.S. Read March 8th, 

 1905.) 



[Plate XXXVII pars.] 



Prof. Groom has sent me some pieces of rock of Silurian age, from 

 Llangadock, containing a number of gasteropoda. These fossils 

 occur almost entirely in the state of internal and external moulds. 

 The former rarely show much structure, but by pressing wax into 

 the latter the original form and ornamentation of the shells are 

 frequently reproduced, in such a manner as to give a tolerably-good 

 idea of the original. By this means I have been able to make out 

 ten distinct forms, which are referable to seven different genera, 

 but only seven are sufficiently well preserved to be specifically 

 determined with any degree of certainty. They may be enumerated 

 thus : — 



Plethospira [Ulrichospira~] similis, Murchisonia [Cyrtostro2)hjf] tor- 

 sp. nov. quata (?) M'Coy. 



Bemhexia (?) Groomii, sp. nov. Loxonema sinuosum (?) Sow. 



Bemhexia (?) sp. nov. Loxonema G-rindrodii (?) Don. 



Bemhexia (?) Lloydii (Sow.). Gyronema Octavia (d'Orb.). 



Murchisonia [Goniostrophd] Cambria, Polytropina globosa (Schloth.) 

 sp. nov. 



Two small external moulds from the Upper Ludlow Beds, of 

 which the wax-impressions bear some resemblance to Gyrtostropha 

 torquata (M'Coy) are too imperfect for certain identification. The 

 same may be said of the much-worn internal mould from the 

 Wenlock Beds, which possibly represents Loxonema sinuosum (Sow.). 

 Besides these doubtful ones, there are three other species from 

 Llangadock which have been previously described by other palaeon- 

 tologists, namely, Bembexia (?) Lloydii (Sow.), Gyronema Octavia 

 (d'Orb.), and Polytropina globosa (Schloth.). They all have a wide 

 range, and cannot be considered characteristic of any particular 

 horizon. Gyronema Octavia (d'Orb.) is by far the most numerous 

 form, there being but few individuals of any of the other species. 



The numerals in parentheses prefixed to the horizons of the 

 several species refer to the specimens in Prof. Groom's collection, 

 and to localities on the map with which he hopes to illustrate a 

 forthcoming paper. 



I must here offer hearty thanks for the facilities afforded me in 

 studying specimens in the Museum of Practical Geology by Mr. E. 

 T. Newton, E.H.S., and Mr. H. A. Allen, and in the Natural History 

 Museum by Mr. E. B. Newton. I am also greatly indebted to 

 Mr. C. D. Sherborn for assistance in looking up references. 



