from the Upper Silurian 4 Wenlock Limestone' of Dudley. 93 



Before the publication of the work of M. de Ryckholt, Mr. 

 King had already announced the occurrence of a Chiton found by 

 Mr. Loftus in the Permian formation near Sunderland*, and 

 described later under the name of C. Loftusianusf, — on this side, 

 M. Philippi having made known two other species (C. siculus, 

 Gray, and C. fascicularis, Linn.) from the tertiary strata of 

 Sicily J. 



After these discoveries, Mr. Salter in 1846 added another and 

 much more remarkable example, that of a species of Chiton from 

 the lower beds of the Silurian strata of Ireland. That author 

 proposed on the occasion a new genus, under the name of Helmin- 

 thochiton, for the purpose of receiving the palaeozoic species §; 

 but as it is not distinguished by any essential character from 

 the ordinary genus Chiton, it can merely serve to denote a section 

 of that genus. 



In 1848 Mr. Searles Wood described and figured, in his mag- 

 nificent Monograph on the Mollusca from the Crag of England, 

 three fossil species of Chiton, one of them being new (C. strigiU 

 latus), and the two others identical with species living in our 

 seas at the present day (viz. C. fascicularis, Linn., and C. Rissoi, 

 Payr.ll). 



About the same date M. Eudes Deslongchamps, to whom 

 science is indebted for a great number of excellent works on 

 the Jurassic fossils of the environs of Caen, discovered in the 

 Bathonian beds of Langrune the posterior or anal plate of a 

 species of Chiton, which he obligingly dedicated to me| — this 

 being the first discovery of the genus in Secondary strata, although 

 their probable existence in strata of that age was some time 

 before predicted by him **, 



In 1852, M. Terquem added a new link to the chain uniting 

 the palaeozoic Chitons to those of the present epoch, by the 

 discovery of a new species (C. Deshayesii) in the middle Lias of 

 Thionvilleff. 



Finally, M. F. A. Roemer described and figured in 1855 anew 



* Ann. & Mag. of Nat. Hist. 1844, vol. xiv. p. 381. 



t Monogr. of the Permian Foss. of England, Pal. Soc. 1849, p. 202. 



% Enumeratio Mollusc. Sicil. t. ii. p. 85. 



§ Synopsis of the Silur. foss. of Ireland by Sir R. Griffiths, p. 74 ; and 

 Quarterly Journ. of Geol. Soc. of London, vol. iii. pp. 48, &c. 



|| Monog. of the Crag Mollusca, pt. 1. pp. 185, &c. Besides these three 

 species, Mr. Wood had also announced three others, which he considered 

 to be new, in his Catalogue of Crag Mollusca published in 1842 (Ann. & 

 Mag. of Nat. Hist. vol. ix. p. 460); but these he appears to have since 

 abandoned. 



*[T Mem. de la Soc. Linn, de Normandie, t. viii. pp. 156, &c. 



** Descript. des Anim. foss. du terr. carb., p. 321. 



tt Bullet, de la Soc. Geol. de France, 2 me ser. t. ix. pp. 386, etc. 



