RHYNCHONELLID.E. 



147 



a glance at their respective figiu-es will easily explain this. It appears to be more 

 variable in shape than P. Knightii. The specimen upon which Dalman founded his 

 species had twelve to fifteen ribs on each valve, and the fold and sinus developed. In 

 some specimens the valves are almost equally and uniformly convex, without fold or 

 sinus ; and while other examples are either smooth or have ribs obscurely marked, some 

 specimens are strongly ribbed. All these variations have been drawn in our plate, and 

 have been selected from several hundred examples. 



Position and Locality. The vertical range and geographical distribution of Pentamerus 

 galeatus is very considerable ; for it is common to the Wenlock, Middle Ludlow, and 

 Devonian formations. It abounds in the Wenlock Hmestone and Upper Wenlock shales 

 near Walsall and Dudley.^ 



Messrs. Phillips and Salter enumerate the following localities : — In Wenlock limestone 

 and shale at Storrige, Ledbury, Eastnor Park and Castle, Dunbridge Wood, east of 

 Ledbury, Brock Hill section, in the Malvern district; at Hill End, and Callow Farm, 

 Abberley district ; east of Canwood, Checkley Common, Dormington Wood, Lindels, &c., 

 in the Woolhope district ; the Rock, ]\[ay Hill district ; Swansea Road and Golden 

 Grove, Llandeilo district. In the Lower Ludlow, at Brock Hill section, Malvern district, 

 and Hill End, Abberley district ; in the Aymestry limestone, west of Rilbiu-y, Malvern 

 district ; Llanbadoc, Beech Hill, Ty-Newydd, Usk district. 



In Ireland, it occurs, with P. Knic/Mii, in the Croaghmarhin (Aymestry) beds^ 

 Ferriter's Cove, Co. Kerry {Salter), and at Cahirconzee, west side (Mus. Geol. Survey, 

 Ireland). It has not been hitherto positively detected in Scotland ; but some casts found 

 in the Llandovery rocks, in the Girvan district, Ayrshire, bear much resemblance to 

 those of the species under description. 



Abroad, it has been found in many countries and locahties. In the Island of Goth- 

 land, it occurs in the "Middle Gothland" of Lindstrom, and thence Dalman's type was 



1 Mr. Allport lias expressed a just regret that it is not a more common practice for collectors to be 

 particularly careful in alBxing the exact localities to their specimens ; as, by making use of the term 

 " Dudley," very much confusion has already arisen as to the Silurian fossils obtained from that district. 

 He remarks that, with regard to deductions made by comparing the fossils from the Dudley shale, sup- 

 posed to represent the Lower Ludlow formation, he does not attach much weight to such comparison, as 

 the rocks near Ludlow are of an arenaceous character, indicating that they were deposited under 

 very different circumstances from the mud beds found near Dudley. Mr. C. Ketley, in an interesting 

 paper in vol. ii, p. 105 (Dec, 1865) of the 'Transactions of the Dudley and Midland Geological 

 and Scientific Society,' seems to consider that, on the whole, the fauna of the upper shale, over- 

 lying the Dudley limestone at East Wren's Nest, Parke's Hall, &c., and which is so well known for the 

 variety and beauty of its fossils, has a closer relationship to the limestone below it than to that of the 

 rocks above. He adds, "Of Brachiopoda the upper shale has twenty-nine species, twenty-four of which 

 are also found in the limestone below. The Lower Ludlow of Ludlow has ten species, of which six ar^; 

 common to the limestone and upper shale also, and two of them to the upper shale." As it must be 

 confusing to some who have not access to the locality, but seek information as to its rocks and fossils, 

 to find this shale named " Lower Ludlow " by one authority and " Wenlock Shale " by another, Mr. 



