344 REPORT—1885, t 
other positions; but not to quite so great an extent, as the shape o 
C. papilio is altered by squeeze in some instances. The valves are 
delicately striate, with longitudinal lines curving parallel with the ventral 
edge, and crowded at the postero-dorsal angles. The body-segments, of — 
which probably five were outside the carapace (though often the seg-— 
ments seem to have been pushed back within the carapace after death), — 
are marked with delicate, raised, oblique, wrinkly lines on the sides, and 
ornamented on the back with an imbrication of angular lines, which pass — 
down into the lateral oblique wrinkles, M. P. G. x 4; and ;},. These © 
joints are sometimes more than twice as high aslong. The last one is 
as long as three of the others. The telson is apparently in some cases 
about half as long again as the stylets (as 50 is to 30) ; and some speci- 
mens show traces of thin costule, and perhaps of prickles. The whole 
adult animals were from 4 to 8 inches long. 
Specimen M. P. G. x 4, has the rostrum and teeth squeezed out 
loose near the front end. A large individual, Cambridge Mus. b/65, 
measures— 
Carapace * -  . 83x55mm. 
Four segments - 40 
Last segment . 95 y sare 
Telson . : ; = 50 “F 
198 mm., or nearly 8 inches. 
A small specimen, M. P. G. x 4;, measures— 
Carapace ; : - 40x 26mm. 
Four segments Be eUa) 
Last segment : SO ape? 
Telson ; , oO ee 
About p - 100 mm., or nearly 4 inches. 
C. stygia was rather larger than C. papilio; its telson was larger; the 
carapace is markedly distinct by its trapezoidal outline, deep ventral — 
region, and mucronate antero-dorsal angle, which was not nearly so — 
often lost in fossilisation as the front angle of O. papilio. In its rostrum, — 
teeth, superficial ornament of carapace and of body-rings, it seems to 
have closely resembled C. papilio. In ten good specimens from Lesma- 
hago, two are simple carapaces; three have body-segments in places, and 
five have them shifted or reversed. In this respect C. stygia seems to 
have been rather less liable to the dissolution of the membranous attach- 
ments of the body than its associate 0. papilio. 
A postero-dorsal fragment in Cambridge Museum (Marr Coll.), from 
the Denbighshire series (Wenlock), at Dinasbran, Llangollen, showing 
fine striz above, and coarse strize below, and the usual convergence of 
striz, belongs probably to C. stygia. 
An anterior moiety of a valve from near Ludlow is in the Grindrod 
Coll., Oxford Mus. G. 
Good specimens of CO. stygia from Lesmahago are Cambridge Mus. 
b/136, b/65 (the last is referred to as C. papilio, evidently by mistake, 
in ‘Cat. C. Sil. Foss.’ p. 178); M. P. G. x jy and +), x py, x 75, X aoe 
x #,; and B. M. 41898, 45154, 45155, 45156, 
In the ‘ Mem. Geol. Surv. Scotl. Expl. Map 23,’ 1873, at p. 49, Mr. R. — 
Etheridge, jun., enumerates the places near Lesmahago and Muirkirk, ing 
Lanarkshire, where Ceratiocarides have been found by the Surveyors, : 
4 
namely— 
y 4 
