231 



Plicatula — continued. 



radiola., rounded; plano-concave upwards; with numerous 

 subsquamous radiating ribs ; margin plaited. , f inch. 



placu7iea. . obliquely oval, plano-concave upwards ; with squa- 

 mous tuberculated radiating ribs and strise ; margin plain 

 . . Env. de Paris ? 



ostreiforme . . rounded, irregular ; with oblique folds, sub- 

 squamous. 



tubifera. . subirregular, varied, windingly flattish ; echinated 

 with short tubular squamae. 



rugosa. . oval, very hollow ; upper valve flat, longitudinally sul- 

 cated ; obsolete, transverse, concentric rugse, margin en- 

 tire. . 2 J inches. 



Spondylus. 



crassicosta. . rounded, very wide ; ribbed and grooved longi- 

 tudinally. 



rastellum. . sublongitudinal, thick, very hollow, ribs and grooves 

 longitudinal, rough, with unequal squamse. . 3 inches long 

 and 2| inches wide. . Turin. 



radula. . obliquely rounded ; with slight longitudinal grooves, 

 rough from squamse ; with others, interstitial, smaller and 

 smoother. . 1- inch. . Grignon. 



podopsideus. . trigono-cuneate, rather smooth on the upper part, 

 longitudinally sulcated, distant tuberculiferous ribs on the 

 larger valve ; tubercles fornicated. . 2| inches. . Havre. 



Podopsis. 



truncata. . longitudinal, wedge-formed, rounded upwards, sub- 

 oblique ; with fine longitudinal striae, sometimes rough with 

 a few spines ; the extended beak crenated. . Touraine. 



gryphoides . . ovato-rotundate, extremely ventricose beneath, 

 smooth, adherent by the larger beak. 



Gryphaea. 



columba. . ovately rotundate, dilated smooth, with a small ob- 

 lique hook, . Mons. 



cymbium. . ovately rotundate, rather smooth, upper valve con- 

 cave, hook slightly oblique. 



arcuata. . oblong, incurved, transversely rugose ; with a large 

 suboblique hook. 

 G. incurva, Sowerby. 



secunda. . oblong, with oblique beak. 



lituola. . larger valve flat on one side ; with tuberculated rib, 

 subcarinated on one side. 



^Zicaf a. .bowed, carinated beneath; folds oblique; with a la- 

 leral hook. .Gazonfier. 



<?is#aw5. .variable, oblong, oblique; hook twisted, lateral ; the 

 folds of growth bowed, concentric and distant. .Mons. 



angusta. .oblong, narrow, curved, obsoletely carinated beneath ; 

 hook lateral. .Rochelle. 



