50 DEVONIAN FAUNA. 



the genus, it seems to be subject to a considerable amount of specific variation, and 

 until further material has been collected it will be impossible to determine the true 

 value of the varieties which are recorded above. One of the specimens described 

 by Jones and Kirkby under the head of Polycope simplex is now regarded by Prof. 

 Rupert Jones and myself as very possibly belonging to the present species.^ 



6. Polycope HuGHESiiB, n. sp. PI. IV, figs. 11 a, 11 &, 11 c. 



Description. — Carapace small, spheroidal, slightly inequivalve. Dorsal margin 

 bearing a slight prominence at its anterior third, marking the position of a definite 

 hinge, behind which the dorsal line is for a short distance straight, before it 

 curves round posteriorly, and in front of which the antero-dorsal margin slopes 

 with a delicate curve towards the front. Ventral margin gently curved. Right 

 valve thickened and apparently overlapping along the antero-dorsal region. 

 Carapace broadly ovate, with valves imperceptibly compressed along the sides. 

 Edge view sub-oval ; end view short, obovate, the greatest thickness being above 

 the median line of the valves. Test thin and sub-punctate. 



Size. — 4 mm. in length. This has been magnified in the figures at a larger 

 scale than the other Polycopes. 



Locality. — Lummaton. A single specimen in my collection. 



Remarks. — The beautiful little specimen here described was found, and given 

 to me on the spot, by Mrs. Hughes, the wife of Professor T. McKenny Hughes, 

 and herself a keen geologist. I have the honour of naming after her the species 

 which she thus discovered. Although capitally preserved, free from matrix, and 

 with both valves in contact, the details of this charming little fossil are at first 

 sight difiicult to decipher. Its valves are perhaps a little squeezed, and the sub- 

 crystalline limestone of which it is composed has a tendency both to mask and to 

 mimic structure. I should not have ventured to separate it from P. Devonica 

 had not Prof. Rupert Jones, who has repeatedly examined it, informed me that he 

 feels assured of its being distinct in its features. It seems to be more angulated, 

 less uniform, and to have less steep sides than that species. It is of a less 

 circular form than P. Burrovii, J., K., & B.,^ more convex than P. simplex, Jones 

 and Kirkby, and more convex than and differently ornamented from P. Yoiingiana, 

 Jones and Kirkby.^ 



' It may be of interest to remark that M. Barrande's Primitia socialis (' Syst. Sil. Bohem.,' vol. 

 i, Suppl., p. 551, pi. xxvi, fig. 11, Et. F) has very much the aspect of a suborbicular Polycope. 

 2 1874, Monogr. Brit. Carb. Entom.,' pt. 1, p. 54, pi. ii, fig. 2. 

 Ibid., p. 5G, pi. V, figs. 2 a—f. 



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