Plate IV. Fig. 15, is one of the cucumerine species of the largest size; 

 and at Plate IV. Fig. 2, is one of the larger areae of one of the mam- 

 millated echinites, with a narrower spine of this species attached to it. 

 These bodies, whose origin was so long a subject of such vague con- 

 jecture, that by some they were supposed to be w r hite pepper in a state 

 of petrifaction, may also now be considered as belonging to this genus of 

 echinites. 



The cylindrical and longitudinal sulcated body, Plate IV. Fig. 13, is 

 sometimes found among the fossils of Shepey Island. Its figure is 

 undoubtedly ambiguous, it having some appearance of a small branch 

 of a tree; I, however, entertain very little doubt of its being part of an 

 echinital spine. 



The small bones and teeth of the echini are sometimes found among 

 the fossil remains of these animals. This has been doubted by some ; 

 but I have no hesitation in saying, that I have some of these fossils from 

 Switzerland. 



LETTER VI. 



FOSSIL SHELLS ARRANGEMENT OF LAMARCK ADOPTED CHI- 

 TON PATELLA. ...FISSU RE LLA EMARGINULA CREPIDULA 



CONCHOLEPAS CALYPTRJEA CONUS CYPRJEA OVULA 



TEREBELLUM OLIVA ANCILLA VOLUTA MITRA......CO- 



LUMBELLA MARGINELLA CANCELLARIA NASSA. PUR- 

 PUR A... .BUCC I NUM ....EBURNA TEREBRA DOLIUM HARPA 



CASSIS STROMBUS PTEROCERA ROSTELLARIA.....MU REX 



FUSUS PYRULA FASCIOLARIA PLEUROTOMA. 



IN OTWITHSTANDING the great degree of judgment displayed by the 

 illustrious Linnaeus, in his systematic arrangement of shells, it does not 

 appear to be proper to adopt his divisions in the present work. It must, 

 I believe, be admitted, that many of his genera are too comprehensive ; 



