22 DR. p. p. CARPENTER ON THE SHELLS OF PANAMA. 



3-42. Calyptrren V.tnigntg, C. B. Ad. =iCrucifjulum spinnfvm, jnn. 

 (not GdhriLs iiiif/itis, IJrod.). 



313. Crcpiilnia rerithiicola. Most of tlic speciiiiciis are the joung 

 of C. onyx, JM. 340 ; but a few are of V. incurva, M. 33'J. 



34-1. Crepidula echinus =C. acuieata, M. 334. 



34"). Vrepidula excavata, M. 33/. > 



340. ('rfj)i(lula 1 hej)afica=C. onyx, M. 340. 



34". i'repidula incurva, INI. 339. A very interestinfj sories of 

 specimens; of which two or three are prohably the tw>steil form of 

 V. onyx. One tray contains specimens adlierinp to other shells. 

 One, fixed diagonally on a Valliostuma, takes exactly the arrow- 

 headed sculpture of the var. Val. imhricata, Brod. Another, prown 

 diasjonally on Pisania yemmafa, has the general aspect of a Chiton. 

 One, fixed on the back of its neighbour which has grown on a Cal- 

 liostoma, has the granular interruptions of the ribs transmitted 

 through the first specimen. The same is true of one which haa 

 grown on another which was planted on a Pisattia. One specimen, 

 which had established itself on a VaUiostoma, and began with normal 

 ribs, is losing these at the margin, adopting the sculpture of the 

 Trochid. An extremely twisted specimen iu the tray of separate 

 shells has a bifid deck. A young one had edged itself into the apical 

 part of the deck, as into a maternal pouch ; so the old one made a 

 fresh deck over it. 



348. Crepidula lessonii. Most of the specimens are of C. nivea, 

 var., M. 341. Two shells, which have the apex perfect, display the 

 characteristic nuclear riblets. One dark-coloured specimen may be 

 a hybrid, and another (though too much worn for confident affilia- 

 tion) ai)pears to be C. nn gin for mis. Among the duplicates, all the 

 specimens which were perfect at the apex presented the niveoid 

 nucleus, though white ; but generally the riblets were more or less 

 worn off. 



349. Crepidula squama. These are the flat form (mostly dead 

 and worn) of C. nivea, M. 341. Some of them pass into lessonii. 

 Some are highly coloured, and may be the young of C. onyx ; one 

 even of C. incurva. One of the young shells in phial appears to be 

 C. onyx ; but whenever the apex is perfect, it presents the typical 

 riblets : v. Maz. Cat. in loco. 



3.50. Crepidula unguiformis. The apex being hidden in dead 

 shells, which I was not at liberty to break away, I could only exa- 

 mine one specimen, which appeared to be a C. nivea, var., as sup- 

 posed in Maz. Cat. p. 28o. Of the loose specimens, scarcely any 

 are sufficiently perfect at the apex to sj)eak with confidence. Most 

 of them, however, have the characteristic painting of the variety 

 g()uuma ; and all may belong to the common species (C. nivea), ex- 

 cept one which is a true C. unguiformis, M. 342, on the back of 

 another shell, and a few which are probably C. onyx, var. Of the 

 d'lplicates, which I was at liberty to extract from the dead shells, 



196 



