130 CARBONIFEROUS L A ME LLI BRAN CHI ATA. 



represented by a few subparallel posterior hinge-teeth in Parallelodon. Doubtless, 

 too, the strige seen in the elongated ligamental area are the homologues of some^of 

 the strise in the anterior portion of the hinge-plates of Myalina and allied genera. 3 

 There seem to be three well-divided sub-groups in the genus Parallelodon, to 

 which, however, I do not propose to give subgeneric names, but merely indicate 

 the subdivisions. 



Group A. With transverse, widely separated, imbricating lamellae : 



P. squamifer. 



P. squamosus. 



P. Vemeuilianus. 



P. cingulatus. 



P. bistriatus. 

 Group B. With reticulate markings : 



P. cancellatus. 



P. reticulatus. 



P. corrugatus. 



P. semicostatus. 



P. Lacordaireanus . 



P. Walciodorensis. 



P. concinnus. 



P. ornatissimus. 



P. tenuistriatus. 



P. decussatus. 



P. fallax. 

 Group C. Surface smooth, with transverse, or with microscopic lines only : 



P. obtusus. 



P. theciformis. 



P. Geinitzi. 



P. Haimeanus. 



P. Fraiponti. 



Parallelodon squamifer, Phillips, sp., 1836. Plate VIII, figs. 4 — 8. 



Modiola squamifera, Phillips, 1836. Geol. Yorkshire, pt. 2, p. 209, pi. v, fig. 22. 

 Non Ctpricardia squamifera, de Koninck, 1842. Anim. Terr. Carb. Belg., p. 92, 



pi. iii, fig. 11. 

 Modiola squamifera, Morris, 1843. Catal. Brit. Foss., p. 92. 



— scalaris, M'Coy, 1844. Carbonif. Foss. Ireland, p. 75. 



— squamifera, Broivn, 1849. Illust. Foss. Conchology, pi. Ixxii, fig. 39. 

 Cfpricardia squamifera, d'Orb., 1850. Prodrome Paleontol., vol. i, p. 130. 

 Omalia squamifera, de Byckholt, 1851. Melanges Paleont., p. 74. 

 Modiola squamifera, Morris, 1854. Catal. Brit. Foss., 2nd edit., p. 210. 

 Cypricardia squamifera, Bigsby, 1878. Thesaur. Devonico-Carbonif., p. 305. 



