ON TUE FOSSIL THYLLOrODA OF THE TALiEOZOIC ROCKS. 65 



Sarthe, Ille-et-Vilaine, and Mayenne, but only one small Ceratiocarid 

 fragment (in the Schisto ardoisiei* inferiear, below the Gres de May), 

 from Laille, was met with, and nothing corresponding to what M. Gaston 

 Le Goarant de Tromelin described as (J. Ceiiomnnensis in <he ' Lettre sar 

 le terrain silnrien de la Sarthe,' addressed to M. Guillier by M. do 

 Tromelin, ' Bulltt. Soc. agriciiltnre, sciences et arts do la Sarthe,' 

 vol. xxii. (1874), pp. 582-590. This work being rather rare, we transcribe 

 the original description (p. 586) : ' Cette espece se distingue de C. Bo- 

 hemicus et C. incequalis en ce qne les trois branches du gouvernail sont a 

 pen pros lisses et n'offient quo quolques faibles rainures longitndinales. 

 La branche principale est plus robuste que les branches secondaires ; 

 tontes trois, assez fortes a leur naissance, se reduiscnt rapidement, et ne 

 paraissent pas d'avoir depasse la longueur de 30 millimetres ; elles sont 

 un pen aplaties dans le sens lateral. Dans tons nos exemplaires elles 

 Bont inclinees a 45 degres par rapport au dernier segment du corps. 

 Celui-ci semble sub-cylindrique, et I'empreinte du test offre qnelques stries 

 longitndinales sans continuite. La forme la plus aiialogao est C. Scharyi, 

 Barr., do Boheme, dont le gouvernail est imparfaitement connu. L'especo 

 portugaise figuree par Sharpe sous le nom de Dithyrocaris lomjicauda ' et 

 la notre ponrraient bien etre idcntiques.' No figure is given. 



M. de Tromelin also determined Ceratiocaris Bohemica, Barr., from 

 Saint-Sauveur (Manche), and C. incequalis, Barr., from Chamire (Sarthe), 

 op. cit. p. 585. 



5. The Ceratiocaris grandis, described and figured in outline by 

 Dr. Julius Pohlman in the ' Bullet. Buffalo Soc. Nal. Hist.' vol. iv. 1881, 

 p. 19, fig. 5, appears to have been a symmotrically oval plate, with sub- 

 acute ends, once convex, but now flattened and marked by a crack on 

 one side, reaching rather more than half-way across. Its relationship is 

 obscure. In size, if the figure be one-fourth more than the natural size 

 (' xi '), the specimen is really about 2 x H inches in dimensions. 



VIII. CariJoUtes {Geratiocaris?). — In the ' Proc. Royal Soc.,' 

 May 8, 1873, p. 289, Dr. H. A. Nicholson, in his paper on annelid marks, 

 noted some fossil ' tracks apparently produced by crustaceans belonging 

 to the genus Geraiiocaris, and for which he proposes the generic name of 

 Caridoliies ' ; distinguishing: them as C. Wibo7ii at p. 290. See also 

 'Geol. Mag.' 1873, pp. 309, 310. The author has very kindly enabled 

 ns to study some of the marks referred provisionally to Ceratiocaris in a 

 dark-grey, finely micaceous, laminated, hard mudstone (Upper Silurian) 

 from Grieston-on-Tweed, in Peeblesshire. The marks are very narrow, 

 some concave (furrows), some convex (casts) ; some nearly parallel, others 

 differing in direction, and nearly all branching off at various angles to 

 apparently tapering terminations. Their origin is obscure. 



IX. Dithyrocaris. — M. Lebesconte's collection, above mentioned, com- 

 prises two specimens of Dithyrocaris, one from Coi'smos (I!le-et-Vilainc). 

 and one from Renaze (Mayenne), both in the ' Schiste ardoisitr supcrieur 

 (Faune 2'^^, Barrande),' above the Gres de May. 



X. Lingulocaris. — Another interesting specimen in 'M. Lebesconte's 

 collection is from the ' Schiste ardoi.sier inferienr (Fauno 2'''^) ' of 

 Angers (Maine & Loire), and very closely resembles Lingulocaris 

 Salteriana, J. and W., shown by fig. 6, at p. 179 of our Sixth Report 



' This is described in detail in our Monngr. Brit. Pal. PhijU., p. Gl, pi. 11, 

 fig. 10. Its generic position is still uucertain. 



1889. p 



