CERATIOCARIS PAPILIO. 37 



In Brit. Mus. 41894, the carapace is 60 mm. long by 30 mm. deep (or high), 

 and probably once rather deeper, having suffered from pressure. The penultimate 

 segment is 10 mm. long, and if there were four of that length (40 mm.), with the 

 ultimate segment (unusually long) the body-rings would be nearly 80 mm. The 

 telson was 25 mm. (stylets 18 mm.). Thus, altogether, the animal was about 

 152 mm., or six inches, in length. 



Brit. Mus. 58669 (PI. XII, fig. 1) has a longer (narrowed) carapace, five 

 body-rings, and a broken telson ; altogether, six and a quarter inches long. 



In another, but smaller individual (Brit. Mus. 41895), the carapace 40x20? 

 mm.; segments 40 mm., but shortened; and style about 20 mm. (stylets 

 15 mm. each), make about 100 mm., or four inches, of total length. 



A specimen at Glasgow has the carapace 50 mm. long, five segments 35 mm., 

 and the style about 25 mm. At Braidwood there is a specimen with the carapace 

 83 mm. long. Of twelve good specimens from Lesmahago we have seen two 

 consisting of carapace only ; and in all the others the body-portion is more or less 

 shifted, and in seven of them it is quite reversed — that is, lying at the anterior 

 instead of the posterior end, as described by Mr. Salter (' Ann. Mag. Nat. Hist.,' 

 ser. 3, vol. v, 1860, p. 154; and ' Siluria,' 1867, p. 236, &c.). 



The specimen Cambridge Museum 6/36 (from Benson Knot ; " G. inornatus, 

 M'Coy," Salter's ' Catal. Camb. and Sil. Foss. Woodw. Coll.,' 1873, p. 178) is the 

 penultimate and ultimate segments, with style and stylet, not crushed, but well 

 preserved in shape, although without ornament (PL XI, fig. 1), of either C. i?apilio 

 or G. stygia, judging from its proportions. 



Of G. papilio, good specimens from Lesmahago :^ 



Cambridge Mus. 6/135, with the rostrum lying at an angle across the anterior 

 extremity. M. P. G. x ^, x ■^. Brit. Mus. 41894, 41896, 41896, 41897, 45161, 

 47989, 58669. Also one in the Museum of the University of Glasgow, and one at 

 least in the Braidwood Museum (from Shanks Castle ; Dr. J. R. S. Hunter). 



We have seen also some fossil carapaces from Benson Knot, Kendal (Upper 

 Ludlow), which agree perfectly in form and proportions with G. papilio from 

 Lesmahago, also in ornament, except that the postero-dorsal convergence of the 

 strise is not present. These are some of those marked 44342 in the British 

 Museum ; M. P. G. x ^ (' Catal.,' 1878, p. 141). They range from 65 mm. long and 

 82 mm. high to 75 X 40 mm. Also a large imperfect specimen and some fragments 

 in brown shale from Linburn, near Muirkirk (Brit. Mus., all marked 58878). 



Moreover, the specimen N in the Ludlow Museum has the proportions and 

 appearance of G. papilio, as far as it is preserved (wanting the antero-dorsal 

 angle), from Church Hill, Leintwardine. 



1 For an account of the Geology of Lesmahago, see H. Woodward's 'Monograph of the 

 Merostomata,' Pal. Soc, 1866, pp. 46—53. 



