POLYCOPE. 49 



This fine fossil dififers from the type in the more elongate and subcuboidal shape 

 of the whole carapace, and from P. Hnghesise in being larger and more symmetrical 

 in outline and in not possessing the well-marked hinge. The marginal edges 

 seem to have a tendency to turn inwards (not seen in the figures), and the surface 

 of the test looks smooth near the edge, but appears to have been obscurely and 

 minutely punctate towards the centre of the valve. The convexity, as seen in the 

 end-view (fig. 13 c), is greatest above the median line of the shell, a feature which 

 seems not unusual in this genus (see also figs. 11 c, 12 c). 



Size. — 7 mm. in length. 



Locality, — Lummaton. 



4. PoLYCOPE Devonica, var. obliqua. PI. IV, figs. 12 a, 12 h, 12 c, 12 d. 



Description. — Valve oval, rather narrow, obliquely rounded at the ends, except- 

 ing that the superior part of the anterior extremity is slightly broken. Moderately 

 and evenly convex, marginal parts steep. Muscle-spot, remaining in the figured 

 specimen where the shell is locally broken away, prominent and ovate, and con- 

 sisting of an irregular double series of low, granulated, radiating ridges. 



The breakage at the anterior end is too limited to allow the supposition of any 

 more beak than such a slight process as is seen in Polycojpe orbicularis, Brady,' 

 and probably there was none at all. 



Size. — 5*5 mm. in length. 



Locality. — Lummaton. 



5. PoLYcoPE Devonica, var. concinna. PI. IV, figs. 17 a, 17 h, 17 c. 



Description. — Valve slightly more orbicular and in outline less symmetrical 

 than in P. Devonica (type), which has steeper marginal slopes, and is almost oval 

 in outline. 



Size. — 6 mm. in length. 



Locality. — Lummaton. 



Remarks. — Since tlie description of this species was first published by Prof. 

 Rupert Jones (1881), I have found a few more specimens of detached valves, but, 

 as far as my experience goes, the species must be regarded as rare. Although there 

 are few details to describe in it, its peculiar contour renders it sufiiciently distin- 

 guishable ; but on the other hand, as in the case of the Carboniferous members of 



' Ibid., p. 471, pi. XXXV, fig. 53. 



