CERATIOCARIS TRUNCATA. 51 



C. Oretonensis differs from the associated G. truncata in being larger, and 

 fuller in the antero-ventral region. Its postero-dorsal slope has a different angle 

 from that of C. truncata, fig. 1. 



PI. X, fig. 4. Brit. Museum No. 58884, from Oreton, Worcestershire (Baugh 

 Collection), is in a drab-coloured, coarse-grained, and partly oolitic limestone; a 

 thin layer of shell remains, but it has been much dissolved. 



20. Ceratiocaeis teuncata, E. Woodivard, 1871. PL X, figs. 1 a and 1 b. 



1871. Ceeatiocaeis tetjncatub, S. Woodward. Geol. Mag., vol. viii, p. 106, 



pi. 3, fig. 2. 

 1878. _ _ _ Catal. Brit. Foss. Crust., p. 72. 



1885. — TEUNCATA, T. E. J. ^ R. W. Third Report Pal. Phyll., 



p. 34.6; Geol. Mag., 1885, 

 p. 461. 



1886. — — — Fourth Eeport, p. 232; 



Geol. Mag., 1886, p. 459. 



The smaller species occurring with G. Oretonensis was described and figured 

 with it in 1871. There are eight specimens in the British Museum, but few of 

 them are at all well preserved. The best carapace measures 35 X 16 mm. The 

 slightly concave truncation of the hinder end is not well rendered in the ' Geol. 

 Mag.,' 1871, pi. iii, fig. 2. Its smaller size, its sharp antero-dorsal angle, and more 

 elliptical ventral curve, distinguish C. truncata from its associate, but scarcely 

 separate it, as far as outline is concerned, from some specimens of G. inornata at 

 Benson Knot. 



Carapace boat-shaped, straight above, elliptical below, curving up less quickly 

 before than behind, where there is a fuller curve going up to meet a truncate edge 

 which slopes at about 60°, with a very slight ogee curve. An indentation and a 

 sharp point mark the front angle. 



This is much like PL X, fig. 2 {G. inornata), but it has a fuller postero- ventral 

 region, and is not so full in the antero-ventral region. The peculiar antero-dorsal 

 angle is not present in G. inornata. 



PL X, figs. 1 a and 1 b. Brit. Mus. No. 58885, from Oreton, is a left valve 

 in Yellow Carboniferous Limestone. 1 a (convex cast) retains a thin whitish film 

 of the test over the greatest convexity ; 1 b (hollow impression) has some of the 

 shelly film still remaining at its ends. 



