CERATIOCARIS COMPTA. 57 



thin sub-ovate carapace excessively fine, parallel, longitudinal striae (PI. X, fig. 12). 

 This form differs from any other we know. Its looseness of structure suggests 

 the name laxa. 



On another of the specimens in the British Museum, marked 59648, from 

 Lesmahago, are three loose small bodies, without carapaces (Third Report, p. 345). 

 The largest has thirteen or fourteen segments (45 mm. in length), some of which 

 are obliquely striate. Five measure 25 mm., and the last one 10 mm., equal to three 

 of the others. The telson is 20 mm. long. Another such specimen, smaller and 

 narrower, 35 mm. long, has fourteen (?) segments ; the last one 7 mm. long ; 

 appendages imperfect. 



These may be the loosened and shifted abdomens of either young individuals of 

 C. stygia or G. papilio, both common at Lesmahago, or more probably of C. laxa. 

 They cannot be mistaken for the Carboniferous Acanthocaris, Peach, or the 

 Devonian Campecaris, Page. 



25. Ceeatiocaeis compta, T. B. J. $• H. W., 1886. PL VII, figs. 10 a, 10 b. 



1885. Ceeatiocaeis cassia (part) , T. B. J. & R. W. Third Eeport Pal. Phyll., 



p.348;Geol. Mag., 1885, 

 p. 463. 



1886. compta, — Fourth Eeport, p. 232 ; 



Geol. Mag., 1886, p. 459. 



The specimen H in the Ludlow Museum, from Trippleton, is a very small, ovate, 

 filmy relic of a valve (13 X 7 mm.), with a loose abdomen of four segments (12 mm.), 

 and a neat little outspread trifid caudal appendage ; style about 10 mm. long, 

 stylets 6 mm. These all are flat, smooth, and thickened at their edges. 



The carapace was subovate, sharp in front, and obliquely truncate behind. The 

 segments, flattened and split along the middle by vertical pressure, are delicately 

 striate (fig. 10 b), with oblique lines (outwards and downwards) on each side, 

 suggesting the name compta, which we propose for this species as being distinct 

 from any known form. 



PI. VII, figs. 10 a, 10 b, Ludlow Museum H, is from the Lower-Ludlow, 

 greenish-grey, finely micaceous mudstone, not calcareous ; and was collected by 

 Mr. Marston at the roadside quarry south-east of Trippleton. 



This small valve is represented by a black film, nearly ovate. The abdo- 

 men and three caudal appendages have been laid out symmetrically by vertical 

 pressure. The oblique lateral striation on the segments is very plain under a lens 

 (fig. 10 &). 



