GASTROPODA. 



Fam. I CHITONIDtE Guilding. 

 Gen. CHELODES Davidson & King. 



1867 Cliiton Barrande Syst. Sil. de Bohéme vol. III p. 175. 

 ' 1874 Clielodes Davids. & K. Qu. Journ. Geol. Soo. p. 167. 



Valves oblong, generally longer tlian broad; no lamince of insertion nor sutural lamince; 

 apical area of the inside higldy developed. 



It was only with sorae hesitation that I placed these curious fossils, of which 

 there are at least two species, amongst the Gastropoda as a genus of the Chitonidae. 

 Led astray by sorae superficial points of reseinblance I at first mistook theni for one 

 of the aberrant group of the Brachiopoda, the Trimerellidas, and accordingly sent the 

 material I then could dispose of to Mr Davidson, when he jointly with Prof. King 

 was working out a Monograph on that group. They described the only form which 

 was then known as Chelodes Bergmani '), stating that it was none of the Trimerellidse, 

 bnt that it rather should be considered as belonging »to a section of the Coelenterates, 

 represented by Calceola and Goniophyllum». The authors do not expressly say whether 

 it should be regarded as the polyparium itself or as the operculum, but it seems most 

 likely, that they have thought the last to be the case. There is, however, no coral in 

 the Silurian formation of Gotland that possibly could have been provided with an 

 operculum of so peculiar a shape. The form of the calyx at its aperture is generally 

 circular or polyedric, never assuming such an outline as Chelodes shows. 



There is not the least doubt that these questionable fossils belong to the same 

 genus as those which Barrande in the third volume of his grand work »Systérne Si- 

 lurien de la Bohéme p. 175, pl. 16 fig. 19 — 28 has figured and named Chiton Bohe- 

 micus. Besides this there are several other pala?ozoic fossils of almost the same shape, 

 which have also been referred to the genus Chiton. Closely related to the Silurian ones 

 are some detached plates, which Kirkby has described and figured with some hesitation 



1) Qn. Jouiual Geol. Soc. 1874, p. 167. 



