part 3] silurian rocks of the clux-fokest district. 231 



by Prof. Garwood 1 in his researches on the Carboniferous Limestone 

 of the Lake District. This general conclusion is borne out by the 

 character of the fossils themselves, as the individuals are all of small 

 size. The only species that seem to retain their normal dimen- 

 sions are Ghonetes striafella and T&eyrichia sp., and, in the case 

 of the former, about equal numbers of very small and normal 

 individuals occur associated together. Spirifera elevata is of 

 moderate dimensions ; but the Orthids are without exception small, 

 and in many cases the specimens of OrtJu's lunata seem to have a 

 shorter hinge-line than in the normal individuals, and thus they 

 resemble 0. elegantula or 0. orbicularis. The change is still more 

 marked in Rhynehonella nucula, a very small form of which is the 

 only Khynchonellid present in the bands. This form is quite unlike 

 the typical Rh. nucula of lower beds, but resembles the specimen 

 figured in ' Siluria ' pi. xx, fig. 2. Mr. S. S. Buckman 2 has expressed 

 his doubts concerning the authenticity of records of Silurian 

 brachiopods, and contrasts the reputed long range of many species 

 with the short range of Mesozoic types. He instances in particular 

 OrtJiia eleyantula — a typical Wenlock form — which is recorded 

 from the Ordovician to the Upper Ludlow. It may be that varieties 

 such as occur in these transitional beds have been mistaken for 

 species described from other horizons. There is need of much 

 detailed palseontological work in connexion with these Lpper 

 Ludlow brachiopods; but the investigation is hampered by the 

 fact that the fossils occur almost exclusivelv as casts. 



(4) The Temeside Group. 



F. Temeside Shales. 



E. Downton- Castle Sandstone. 



E. Downton-Castle Sandstone. — In the Ludlow district, 

 notably at Downton Castle, the summit of the L T rjper Ludlow 

 Series is well defined by the presence of the Ludlow Bone-Bed : 

 accordingly there is no difficulty in determining the lower limit 

 of the Temeside Group. The lower of the two divisions of the 

 Temeside Group has been called the Downton-Castle Sandstone. 3 

 At Ludlow, in the Ludford-Lane section, the strata immediately 

 succeeding the Ludlow Bone-Bed are 'mottled sandstones and 

 shales' 4 about 3 feet thick, with a Bey rich ia Band at the 

 top and followed by an argillaceous Platyschisma Bed. Farther 

 west, at the Downton-Castle inlier, the same beds are noted as 

 * mottled sandstone,' 5 still about 3 feet thick, and succeeded by 

 the Platyschisuia Band. Similar beds occur at Downton-Castle 

 Bridge, and there they take on a character which is of particular 



1 Q. J. G. S. vol. lxviii (1912) p. 455. 



2 Proc. Geol. Assoc, vol. xviii (1904) p. 454. 



' A G. L. Elles & I. L. Slater, Q. J. G. S. vol. lxii (1906) p. 199. 



4 Ibid. p. 203. 



5 Ibid. p. 210. 



