BIVALVIA. 9 



The variety called cylindrica or cymbiformus (fig. 3, c), is also occasionally found ia 

 the CoraUine Crag, though by no means abundantly. It has been determined by 

 British Conchologists, that this form is produced from its place of adherence being the 

 stem of the seaweed, or some such cyUndrical body,* while the variety fornicata 

 is said to be merely a deformity from some similar cause ; this I have not yet seen 

 in the fossil state. The exterior of some of the Crag specimens indicate their place 

 of rest to have been upon a Bri/ozoon, the shell being prettily and distinctly marked by 

 that animal. 



Some idea may be formed of the Protean character of this species, as no less than 

 eighteen different specific names are introduced by the authors of the ' Hist, of Brit. 

 Moll.' into their synonyma, while these, with several others by them, considered 

 as distinct, are included as mere varieties by Mr. Clark. 



2. Anomia aculeata, MilUer. Tab. I, fig. 2, a — b. 



Anomia aculeata. Mull. Zool. Dan. Prod., p. 249, 1766. 



— — Mont. Test. Brit., p. 157, pi. 4, fig. 5, 1803. 



— — Brown. Brit. Conch. Illust., pi. 34, fig. 6, 1827. 



— — S. Wood. Catalogue, 1840. 



— — Gould. Invert. Massach., p. 139, fig. 90, 1841. 



— — Philippi. En. Moll. Sc, vol. ii, p. 214, t. 28, fig. 1, 1841. 



— — Thorpe. Brit. Mar. Conch., p. 123, fig. 73, 1844. 



— — Loven. Ind. Moll. Scand., p. 30. 



— — Deka>/. Nat. Hist. New York (Zool.), p. 168, pi. 12, fig. 210. 



— STRTOLATA. Turt. Brit. Biv., p. 233, 1822. 



— — W. Wood. Ind. Test., p. 54, pi. 11, fig. 7, 1825. 



— — Flem. Brit. An., p. 396, 1828. 



— — Thorpe. Brit. Mar. Conch., p. 123, 1844. 



Spec. Char. Testa suhorbiculari vel ovatd ; striata, striis plurimum numerosis, radian- 

 tibus, squamoso-aculeatis ; mnbone submarginali, Itsvi. 



Shell suborbicular or ovate ; striated, striae generally numerous, with fine elevated 

 or squamose prominences, rendering the surface rough or prickly ; umbo, submarginal, 

 and smooth. 



Diameter, \ an inch. 



Locality. Cor. Crag, Sutton, and Ramsholt. 



Recent, Mediterranean, Britain, Scandinavia, and North America. 



This species, called the prickly Anomia, is very abundant in the Coralline Crag at 

 Sutton, whence all my numerous specimens were obtained. I have not yet seen it 

 from the newer formations. It closely resembles the young of the preceding in most 



* This, however, was not the position of our shell, which is the upper or imperforate valve, and is 

 quite flat, the lower or adherent one, was probably convex externally, and fixed to the interior of some 

 cylindrical body, and to which our specimen must have acted as a lid. 



2 



