﻿'Vol. 66.'] TRILOBITES FROM THE CA3IBRIAX ROCKS OF COMLEY. 19 



j2. On some small Teilobites from the Cambrian Rocks of Comley 

 (Shropshire). By Edgar Steelixg Cobbold, F.G.S. (Read 

 December 1st, 1909.) 



[Plates HI-VIDE.] 



The trilobites described in this paper were mainly collected during 

 the progress of the excavations at Gomley, which formed one of 

 the subjects of the Report x of the Geological Excavations Committee 

 ►of the British Association, read at the Dublin Meeting, 1908. 



The majority of the specimens were derived from the preliminary 

 excavation in the fields, some 200 yards south of the well-known 

 Comley Quarry. This excavation cuts transversely through the 

 •same set of beds as those that are worked in the quarry, and, 

 though of only a very shallow depth, it exhibits the most complete 

 section as yet exposed of the local junction between the Olenellus and 

 Paradoxides divisions of the Cambrian. Between the Olenellus 

 Limestone, which in the quarry yields Olenellus (Hohnia) callavei, 

 Lapw., and the Conglomeratic Grit, which in the same quarry 

 yields Paradoxides groomii, Lapw., 2 there is intercalated some 

 4 feet of grey limestone. Provisionally, I divide this into the 

 .following bands, in descending order (see text-fig., p. 20) : — 



Thickness in inches. 



Conglomeratic Grit (Paradoxides). 



Black Limestone 12 



Grey do. Uppermost part 3 



Do. do. Upper part 6 



J)o. do. Middle part (reddish purple) ... 12 



Do. do. Lower part (greenish grey) 9 



French Grey Limestone 6 



Olenellus Limestone. Olenellus (Holmia). 



1 hesitate to assign any definite numbers or letters to these beds, 

 until more is known as to their faunal characteristics, which 

 will throw light on their natural grouping. All these limestones 

 above the Olenellus Limestone contain black nodules of, probably, 

 phosphatic matter. 



The trilobites occur as aggregations of many parts or fragments 

 of parts, indiscriminately mixed three or four species together, and 

 usually preserve their original form and convexity. In most cases 

 the test has also been preserved, either wholly or in part: and 

 where this has been the case I have often been enabled to correlate 

 free cheeks, pleurae, etc. with the cranidia, in a way that would 

 have been quite impossible if the surface characters had not been 

 retained and propinquity only had to be relied upon. In the 

 descriptions I have set forth the evidence upon which I have relied 

 in making my correlations, so that future workers may be able to 

 distinguish between what is actual fact and what is only matter 

 of inference. 



1 Rep. Brit, Assoc. 1908 (Dublin) 1909, pp. 231-42. 

 - Geol. Mag. dec. iii, vol. viii (1891) p. 532 & footnote. 



c 2 



