326 ME. E. S. COBBOLD ON THE [vol. lxxvi, 



differ considerably from those now proposed, a few words of 

 explanation seem to be necessary. 



As the study of the fossils collected from the different beds 

 proceeded, it became apparent that they might prove to be of more 

 than local interest, and it was therefore desirable that the original 

 indefinite or cumbersome terms, based on local names, or lithological 

 variations, should be abandoned in favour of others based upon the 

 fossil contents. It was also evident that, in several instances, beds 

 or groups of beds, to which a local name had been allotted, con- 

 tained more than one set of fossil forms, and it seemed undesirable 

 to resort to any extended use of such terms as Upper, Middle, 

 Lower, etc. 



Thus the ' Lower Comley Sandstone ' has been divided into five 

 parts, and the three divisions previously called ' The Grey Lime- 

 stones,' ' The Black Limestone,' and ' The Shoot-Rough Road 

 Flags,' into two horizons in each case. 



III. Classification, Terminology, and References. 



The classification and terminology used in the descriptions of 

 the brachiopoda follow closely those adopted by Dr. C. D. Walcott. 

 In view of the very full references given by him, it has not been 

 considered necessary to quote more than (1) the work in which 

 any species was first described, (2) the pages, plates, and figures in 

 his monograph, and (3) any references to works later than those 

 to which he had access. 



In order to avoid repetition, works enumerated in footnotes are 

 designated by the names of the authors and dates. The full refer- 

 ences may be found hj referring to the Bibliography. 



I have followed the usual practice in including such tubular 

 fossils as Hijolitliellas, Selenia, etc. among the Pteropoda, but 

 .am doubtful whether they really belong to that order. 



IV. Bibliography. 



J. Barrande. 1867. — ' Systeme Silurien de la Boheme : vol. iii — Pteropoda.' 

 E. Billings. 1861. — Geol. Surv. Canada. ' Palaeozoic Fossils ' vol. i. 

 E. Billings. 1872. — Can. Nat. n. ser. vol. vi, pp. 465-80. ' On some Fossils from 



the Primordial Rocks of Newfoundland.' 

 C. Callaway. 1874. — Q. J. G. S. vol. xxx, p. 196. ' On the Occurrence of a 



Tremadoc Area near the Wrekin in South Shropshire.' 

 C. Callaway. 1877. — Ibid. vol. xxxiii, pp. 652-72. ' On a New Area of Upper 



Cambrian Hocks in South Shropshire.' 

 C. Callaway. 1878. — Ibid. vol. xxxiv, pp. 754-63. ' Quartzites of Shropshire.' 

 E. S. Cobbold. 1909.— Rep. Brit. Assoc. 1908, Dublin, pp. 231-42. ' Report on 



some Excavations in the Cambrian Rocks of Comley (Shropshire).' 

 E. S. Cobbold. 1910a.— Ibid. 1909, Winnipeg, pp. 181-86. 'Report on some 



further Excavations among the Cambrian Rocks of Comley (Shropshire).' 

 E. S. Cobbold. 1910 b.—Q. J. G. S. vol. lxvi, pp. 19-51. ' On Trilobites from the 



Cambrian Rocks of Comley.' 

 E. S. Cobbold. 1911a.— Rep. Brit. Assoc. 1910, Sheffield, pp. 113-22. 'Third 



Report on Excavations among the Cambrian Rocks of Comley.' 

 E. S. Cobbold. 19L1 b.—Q. J. G S. vol. lxvii, pp. 282-311. 'Trilobites from the 



Parado.rides Beds of Comley.' 

 E. S. Cobbold. 1912.— Pep. Brit. Assoc. 1911, Portsmouth, pp. 111-15. 'Fourth 



Report on Excavations among the Cambrian Rocks of Comley.' 



