50 BRITISH PALtEOZOIC PHYLLOCARIDA. 



This is neai' C. inornata, M'Coy, but far more convex on the postero-ventral 

 border, and more fully rounded behind ; thus differing in its proportion and shape. 



It lies in the usual dark-grey sandstone, micaceous, slightly calcareous on the 

 edges, and containing remains of bivalve shells. Longitudinal striee are visible in 

 certain lights on the thin brownish film left by the test. The valve is broken and 

 imperfect. It has a strong rim on the ventral margin. The central spot is due to 

 an accidental blow. 



19. Ceeatiocaris Oeetonensis, H. Woodivard, 1871. PL X, fig. 4. 



1871. Ceeatiocahis Oeetokensis, S. Woodward. Geol. Mag., vol. viii, p. 105, 



pi. 3, fig. 1. 

 1878. _ _ _ Catal. Brit. Foss. Crust., 



p. 71. 



1885. — — T.B.J.Sf H. W. Third Eeport Pal. PhylL, 



pp. 346; Geol. Mag., 

 1885, p. 461. 



1886. — — — Fourth Report, p. 232; 



Geol. Mag., 1885, p. 459. 



This Carboniferous species, described in the ' Geological Magazine ' for March, 

 1871, approaches closely to some of the forms of Geratiocaris found in the Upper 

 Silurian of Benson Knot. The carapace (50 X 24 mm.) is larger than C inornata, 

 M'Coy ; but does not attain the size and proportions of C. papilio. In re-exa- 

 mining the specimens we find that the anterior end is not so much rounded 

 as in fig. 1 of pi. 3, ' Geol. Mag.,' 1871, but is slightly and obliquely truncate ; 

 and the antero-ventral margin is more sloping and less convex ; thus the greatest 

 depth of the carapace is in the hinder half. The possible "eye-spot" mentioned 

 at p. 105, oj)- c'd., is too indistinct to be at all recognisable as such. There are 

 four specimens in the British Museum from the Yellow Carboniferous Limestone 

 of Oreton and Farlow, Worcestershire, not well preserved. 



Carapace boat-shaped, convex, straight on the back, elliptical below, with the 

 postero-ventral margin more boldly curved than in PI. X, fig. 7 a, and even than in 

 figs. 2, 3, and 5. The mid-ventral border is not nearly so deep in proportion as in 

 fig. 7 a. The antero-ventral border is more convex than in the others here referred 

 to. The hinder margin of the best specimen (here figured) , is imperfect, but appears 

 to have suddenly sloped off (at an angle of about 35°) from the dorsal edge to a 

 well-curved end. An antero-dorsal angle was probably present but is now 

 wanting. 



