EURYPTERUS PYGM^EUS. 145 



together in masses, and occasional traces of Pterygotus." The uppermost beds, about 

 twelve feet in thickness, are composed of three beds of bluish-white stone, very hard, 

 close-grained, and unfossiliferous. 



" Between these upper beds and the underlying bed is a greyish layer, varying from 

 three to six inches in thickness, occasionally of a blackish-grey colour, from the quantity 

 of vegetable remains mixed up with it, and containing on the western side of the quarry 

 the remains of Fish (Pteraspis) and of Pterygotus and other Crustaceans. This layer, 

 when dry, is tough, and the remains are with difficulty removed from it ; but when 

 placed in water it separates easily, wherever the remains occur, and if left in water soon 

 decomposes into mud. It appears to have been just such a muddy sediment, accom- 

 panied with sea- weeds, as was suited to Crustaceans. The organic remains in this layer 

 retain their dermal covering, which is often glossy, and in a more perfect state than in 

 the underlying beds of Downton Sandstone. Small, round, rusty nodules, sometimes 

 irregular, occur in this layer in abundance, but no Mollusca. 



" The next bed, which is probably identical with the Downton Sandstone, consists of 

 a yellowish-white, close-grained sandstone, on the east side of the quarry passing 

 gradually into a blue and still harder stone, which contains occasional traces of Pterygotus, 

 but more frequently Lingula cornea. The yellow portion of this bed contains throughout 

 Pterygotus and fish remains {Pteraspis), with an occasional Trochus helicites, but they are 

 not so abundant as in the grey layers and underlying bed. This bed is from three to 

 four feet in thickness. 



" This is followed by a grey layer, similar in composition and contents to the grey 

 layer already noticed. The next or bottom bed of the quarry is a yellow sandstone of still 

 better quality, capable of being dressed to a very fine surface, and much used in building. 

 It is about four feet in thickness. The lowest portion of it consists in many parts of the 

 quarry of large flagstones, from a foot to eighteen inches thick, used for gravestones ; 

 these lie on the Ludlow Rock, here a very hard unmanageable stone, termed by the quarry- 

 men ' greenstone.' The Pterygotus and fish remains occur down to the very bottom, 

 where the spines of Leptocheles first appear in considerable abundance ; Trochus helicites, 

 much depressed, and the small Lingula before noticed, also occur in the lowest portions 

 of the bed." l 



Mr. Banks adds : — " A specimen of a Crustacean, probably a species of Eurypterus, 

 was found in the grey layer before noticed ; it is very imperfect ; the trace of the dermal 

 covering is slight, and the posterior segments, which would throw a greater light on its 

 proper position, are wanting. The posterior portion of the head, at the junction with 

 the thorax, is bounded by an almost straight line, of an equal width with the bands, 

 which are entire from side to side and without any longitudinal depression. Mr. Salter 

 proposes to name it E. pygmaus. One specimen which I lately found had a distinct 

 swimming-foot on the left side, resembling those figured by various authors who have 



' R. W. Banks, 'Quart. Journ. Geol. Soc.,' 1856, vol. xii, pp. 94 and 95. 



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