gavey lower lias, gloucestershire. 35 



Crustacea. 

 Three species. Two are new forms belonging to the family Asta- 

 cidce; and the other is a new species allied to the genus ^ya*. 



About four miles S.S.E. from Mickleton Tunnel is another cutting 

 of some interest, through a low ridge branching off from the Cottes- 

 wolds at the village of Aston Magna. 



The cutting in question lies north and south, which gives a trans- 

 verse section of the hill. See PI. I. section, fig. 3. From the 

 north end to the centre of the cutting the upper bed consists of a 

 thick accumulation of gravel, sand, and clay, derived from the Infe- 

 rior Oolite. This is not disposed in layers, but forms an unstratified 

 deposit, capping the summit of the hill, and containing large blocks 

 of the same formation lying in various positions. From the centre 

 of the cutting this deposit becomes mixed with a large quantity of 

 small chalk-flints, which are common in the neighbourhood. It may 

 therefore be inferred that this accumulation of oolitic gravel, &c., 

 consisted of the debris of the Cotteswold Hills during their denuda- 

 tion, but which had not been long subjected to the action of water, 

 for the gravel and blocks of oolite bear no appearance of having been 

 rolled, and differ very much in this respect from the large deposits of 

 rolled oolitic gravel near the village of Paxford, about two miles 

 distant from this point ; neither had the few fossils (chiefly Tere- 

 bratulcB) which I found any appearance of being waterworn. 



In the centre of the cutting, and lying immediately under the 

 above-mentioned oolitic gravel, &c., is a thick deposit of very large 

 chalk-flints, many of them weighing one and two cwt. each. They 

 are not waterworn, and retain their original white coating uninjured. 



These are intermixed with blocks of hard Chalk, Greensand, and 

 clay, together with a quantity of siliceous sand and pebblesf . The 

 greatest thickness of this bed is about 1 7 feet ; it is 200 feet long, 

 thinning out north and south. 



I collected a few Terehratulce from the blocks of Greensand, but 



* Mr. Salter remarks on this fossil, " I have compared it, with Mr. Adam White's 

 help, with Cymothoa and its allies. The genus jEga, a near ally of Cymothoa, pre- 

 sents the most resemblance to the fossil in the shape of the rings and the strong 

 impressed line which traverses them. But your specimen has the eight anterior 

 rings preserved, and the sixth and seventh are nearly of the same width, a charac- 

 ter which makes it more like a Cirolcena : C. hirtipes is the species which has been 

 compared with yours. Both jEga and Cirolcena occur in Britain, and both are 

 parasitic upon fish. The fossil is a very good specimen. The anterior ring, just 

 behind the head, is notched for the reception of that part, but it is unfortunate that 

 the sides are not more cleared, as they would probably show a granulated surface. 

 Though I have mentioned Cirolana as being its near ally, it is more probably a 

 distinct genus either from that or ^ga, for in both these genera there is a sudden 

 change in the form and size of the segments, at the sixth in ^ga, at the seventh 

 in CirolcEna. Now, your specimen has no decided change ; the seventh and eighth 

 are only a little narrower than the preceding ones. If I were to refer it to any 

 existing genus, I should say jEga, the general surface and habit being very nearly 

 like that genus." 



t This debris of flint and greensand seems to indicate an extension of the Chalk 

 and Greensand beds at a former period above the Oolite of this district. — [Note 

 bv Rev. P. B. Brodie.] 



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