185 



porosa lavis, and is thus spoken of by this writer * : " Ex plurimis conehis 

 lapideis atque conchitis in Helvetia passim reperiundis, quorum descrip- 

 tionem Operi ipsi Historico-Helvetico-Naturali reserve, aliquos duntaxat 

 sisto, rariores scilicet, et ab aliis non, vel obscure descriptos, quos inter 

 primum commemoro Concham fossilem Tellinoidem, ita mihi nuncupatam 

 quia cava est, sui similem marinam, plane repraesentans, et Tellinse for- 

 mam rhomboidalem exprimit ; ab una cardinis parte, eaque nunc dex- 

 tra, nunc sinistra (un.de non univalvem, sed bivalvem quoque dari, vel 

 primitus fuisse conjicio) longius excurrit alterutrum latus, idque recta 

 prorsus linea, dum latus brevius nunc sese incurvat, nunc, et plerum- 

 que, rotundat. Structuram quod attinet, est ea rara admodum, porosa, 

 Tro^urpjjT^, poris non in superficie tantum eonspicuis, sed totam eamque 

 insignem crassitiem perforantibus, eo plane modo, quo astroitarum pori 

 et stellulae totam, plerumque massam penetrant. Cavitas interna est 

 lievis, et tamen lineis ab uno latere ad alterum transversim excurrentibus 

 notata. Caeterum friabilis est et ita fragilis ut rarissime reperiatur inte- 

 gra, nunquam prorsus bivalvis, et ideo lapidis nomen vix promereatur, 

 nisi porosioribus et mollioribus accensere illam velis. Habeo et frustulum 

 conchse violentia quadam contortse sen compressae. Color plerumque 

 est cinereus, aliquando subpurpureus, et rubiginosus." 



M. Walch says very little respecting this curious fossil. M. Bertrand, 

 with M. Davila, suspected these fossils to be the valves of a shell resem- 

 bling Lepap anatifa ; forming their conclusions on the accordance of their 

 figure with that of the valves of the Lepas, and on the two valves not 

 being ibund together, as they think would be the case if the shell was a 

 bivalve. Baier, however, has engraved six or seven specimens in which 

 the two valves have been found together, although open. Monum rer. 

 pctrif. Tab. xiv. This author considers these shells as Chanue and Tel- 

 lens; even referring one species to T. rostrata, Linn. Neither Lamarcl^: 

 nor Faujas St. Fond have made any mention of this shell. 



* Specimen Lithog. Helvet. p. 21. 

 VOL. III. 3 B 



