FAMILY 4. PECTINACEA. 161 



PI. CXIV.* Fig. 6. 

 Pecten asper, Sowerby, Jun., Thesaurus Conchyliorum, Part 2. 



PI. CXIV.* Fig. 7. 

 Pecten sauciatus, Lamarck, Anim. sans vert., new edit., vol. vii. p. 142. 



Chemnitz, Conch., vol. vii. pi. 69. f. H. 

 Ostrea sauciata, Gmelin. 



PI. CXIV.* Fig. 8. 

 Pecten superbusI, Sowerby, Jun., Thesaurus Conchyliorum, Part 2. 



PL CXIV.* Fig. 9. 

 Pecten bifrons, Lamarck, Anim. sans vert., new edit., vol. vii. p. 131. 

 Delessert, Recueil de Coquilles, pi. 15. f. 5. a, b, c. 



PLICATULA, Lamarck. 



Testa affixa, irregularis, inaequivalvis, inauriculata, basi attenuata ; mar- 

 gine superiori rotundato, subphcato ; umbonibus inaequalibus, area 

 externa nulla. Cardo dentibus duobus, in utraque valva valide 

 intersertis, ligamento interno in fossula intermedia affixo. Impressio 

 muscularis sublateralis, distincte imbuta. 



The Spondylus plicatus of Linnaeus was selected by Lamarck as a type 

 for the formation of the present genus, because its shell exhibits certain 

 characters which he considered as intermediate between those of the 

 genera Pecten and Spondylus. Like the former, it has no basal area or 

 disc ; like the latter, it becomes attached by the lower valve, and the 

 hinge is furnished with teeth. It may be observed, however, that the 

 Plicatulae are much more closely allied to the Spondyli ; in fact, many 



t The description of this beautiful species, from Mr. Cuming's collection, will shortly be 

 published in the new Thesaurus Conchyliorum, by Mr. G. B. Sowerby, Jun., a work which is 

 intended to consist of a series of Monographs illustrated on a more economical plan than has 

 yet been attempted. 



VOL. I. Y 



