In the dentition of tlip rij^ht vnlve tliis ^ouws ro«pmI)les Ctrfodotif 

 except that tlie posterior lamina is greatly developt-d, resembling a 

 divide. Tlie left valve wants the central toutli and diatnliernf" tl.it 

 geinis. This strnctnral deficiency, however, is conipcnsati'd by the 

 development of an ossicle in the long cartilaire. As far as is known, 

 all the species are from North and Central America, and are swollen 

 ventrally. 



2. ClIDIOPHORA CRISTATA. 



C. t. securi/ormi, uiinus trans^eri»a, fennf, suhplnnata ; timboni- 

 biis ad t lonffitiidiiiis sitis ; rent; af Her miixime excuri'ata ; 

 mnrfiinihiiH dorsal ihiis, post, mrixime tuciirrnto, ant. h'>r et illlc 

 alulis trianyularihua cristato : i/ifnx ttninjiuibiis pos'icis utra- 

 que in ra/ra erectis : v. dextr. deiitc posttco satis Umyo, cicO' 

 trice adductoris tenus hand porrecto ; dente centrali extunte ; 

 dente anticn <i maryive separata, usque ad cic. aiiticum porrecto, 

 haud extante : v. siiiistr. dente post, bifida, hand eufante, ul- 

 teruni recipiente, fossa cartilayiiien coiifiyuit ; d. centr. tiullo ; 

 d. ant. satis extante, usque ad cicatr. ant icam porrecto ; tinea 

 palliari a uiaryme ralde reinata, reyulariter in puncta divisa ; 

 radiis ab umbonibus usque ad puncta cunspicuis, cequulibua ; 

 ossiculo tenui, elongato. 

 Long. 1"0, lat. "6, alt. -1 poll. 



Hab. in sinu Californiensi ; legit Conway Shipley diligentissimusj 

 sp. nn. in Museo Cuniingiano. 



This species is known from C. claviculata by the much greater 

 posterior curvature of the beaks, and anteriorly by the bciiutiful tri- 

 angular wing-like serrations of the margin, in which it resembles 

 Tellidora burneti. The inside has elegant rays from the umbo to 

 the dotted pallial liue. 



3. Clidiophora tabacea, Meusch. (Mas. Gron.). 



Specimens under this specific name are preserved in the Cumingian 

 collection. 



3 a. Clidiophora trilineata, Sav (^Pandora tr.), Ilanl. Rec. 

 Shdls, p. 49. 



3 b. Clidiophora nasuta, Sby. (^Pandora n.), Sp. Conch, f, 

 18, 19. 



It is probable that these are simply varietal forms of the well-known 

 New England species. Say's name and Sowerby's excellent figure 

 prove that the peculiar hinge of the genus was observed by both 

 authors. Mr. Cuming gives "Philippines" as the habitat of his 

 specimens of C. nasuta, probably in error. Mr. Ilanley quotes it as a 

 synonym of C. trilineata. An examination of a large series from Staten 

 I:>land proves that the outhue varies considerably. The tablet in 

 the Nuttallian collection at the British Museum, marked Pandora 

 punctata, belongs to this species. Young shells, when quite perlect, 



226 



