188 CRETACEOUS PELECTPODA 



Only tlie type species Card. Balinensis is sufficiently well known, it is a Jurassic 

 form; but it seems, as Mr. Laube remarks, very probable that some more species 

 will be shown to belong to this genus ; he already quotes Isoc. minima of '^owerby 

 and Isoc. gibbosa of Miinster. The cretaceous formation will very likely have 

 also its contributions, but I have not come across a single form from tertiary beds. 



10. Glossus, Poll, 1791, fBucardia et Isocardia auctorum). Shell ventricose, 

 concentrically striated and covered with an epidermis, beaks distant, strongly 

 incurved and bent outwards, a ligamental groove extending from them posteriorly; 

 hinge with two cardinal and one posterior lateral tooth in each valve, all arranged 

 parallel to the hinge margin ; right valve with the supero-posterior cardinal tooth 

 long and imperfectly divided by an oblique furrow, the anterior portion being 

 separated from the single antero-inferior cardinal tooth by a deep longitudinal 

 pit; left valve with the postero-superior cardinal tooth long, lamelliform, sim- 

 ple, and with the antero-inferior cardinal more prominent, both being separated 

 from each other by a long groove, the latter also is divided by an oblique furrow 

 into two parts, the anterior portion possessing below a small pit for the lower 

 tooth of the right valve. The only known recent species is the well known 

 Glossus fisocardiaj cor, Linne; it also occurs in the European and North 

 American upper and middle tertiary beds, at least the various forms described 

 under different names have lately all been identified with the recent species. In 

 spite of the very numerous fossil species described as Isocardia (■= Glossus), I 

 do not know a single one which would exhibit an arrangement of the hinge- 

 teeth identical with the type species ; and until this has been shown we cannot 

 speak of fossil species of Glossus. The cretaceous I. similis of Sower by seems 

 to be the nearest approaching to the type. 



Having thus to deal with a single species of the genus, its nomenclature 

 is easily settled. Our shell was known to Scilla and Lister, who called 

 it Bucardia, but I do not think it can be said with the classificatory spirit of 

 Linne, though probably with the intention that this designation should distin- 

 guish the shell in question from others. Klein in his " Tent, meth.," 1753, 

 p. 140, classed our shell in his genus Isocardia, what he calls the second 

 species — IcBvis, which he divides into Bucardia and Camadia : the former he 

 again divides into six groups, and as the second of the series he quotes Lister's 

 shell. It is clear that this arrangement can have no claim upon our system of 

 nomenclature, though mutatis mutandis it is correct that Linne's Chama cor 

 was included in what Klein called a genus Isocardia. In 1791 Poll described our 

 shell as Glossus ^^ubicundus and the animal as Glossoderma. The former is the first 

 distinctly generic name together with a specific one ; the latter must be replaced by 

 ' cor' of Linne, but the former evidently has full authority. If we apply the strictest 

 scrutiny to these facts we cannot justly dispense with Poll's name Glossus. Eor, 

 though Lamarck introduced Klein's name Isocardia already in 17^9, he quotes 

 Linne's species only in 1819 as Isoc. cor, after it had been in 1811 called by Meg. v. 

 Miihlfeld Bucardium, and in 1817 by Sc]iulimach.eT Bucardia communis, Klein's 



