139 



1 —Ccecum nitidum, Stimps. Mfonogr. Caac. U.8. in Pro I 

 X. II. S.Oct. 15th, 1851, p. I 12*. 



While size and shape arc tolerably good guides in examining adull 

 Ckeca, they afford very little character in M< \- the adull 



shell might be formed either out of a bend in the Bpire or a straight^ 

 ened prolongation, it might assume the peculiar form of the spe< 

 or a thinner, longer condition. The spiral formation also gives more 



Or less of twist to the axis even of the adult shell, which CS 



ciinens to roll over at a touch, and makes the examination even of 



the profile of the plug a matter of difficulty. The same caU8e mas 

 also make the shape of tlft plug itself not quite 80 constant BS QSUa] 

 More than 150 specimens have been examined, of which 

 sessed their opercula. 



Test, adolesc. long. '058, lat. 006— *02. 



Test, adult, normal, long. -088, lat. '013— '027 



Test, adult, clone;, long. *091, lat. -014— •()•_';. 



Test, adult, obes. long. -068, lat. 015— -03. 



Ha b. W. Indies, in shell sand, and sponge of commerce ; fossil 

 in coral rock, Barbadoes {Dr. Cutting) ; '. Florida (Stimpson). ' I 

 Brit. See. 



10. Meioceras cornucopi.e, n.s. 



M. t. "M. nitidum " rimulante; eed minore, minus inflata; I . <t<ht- 

 lesceitte anfractibus mini's rapide augentibus; aepto mucro- 

 nato, mucrone acutissitno, haud elongate, a auperficie subplanato 

 snl, itn ascendente ; margine laterali valde incurvato : oper- 



eulo .'.... 



Yariat mucrone elevato. 



Test. jun. long. -048, lat. 007— *015. 



Test, adult, elong. long. "09, lat. '012—02 



Test, adult, compacta long. -064, lat. 013— '018. 



Ahout 120 specimens were found, of which one apparently 

 I a thin, scarcely concave operculum. A high power, however, 

 displayed a texture without trace of spiral elements; and ii n;i> pro- 

 bably formed of adventitious matter. Some forms of this sp 

 run into aherrant forms of the last : hut it may in general be easily 

 distinguished, in the young shell by the more gradual increase; in 

 the adult by the small size and slight inflation; and in all Btages by 

 the very sharp mucro, with concave sides. 



Hub. W. Indies, in sponge of commerce. 



1 I . MEIOCEB kS I ORNTJBOV1S, U. S. 



M. t. " M. cornucopiam " eimulante; ted tepto tubungulato; 

 apice angusto, aubmucronato ; margine laterali /•' 

 eont infiato : opercula aatit 



ir. Stimpson'a diagnosis does not speak of the plug, .iml night accord with 

 any of the three species here proposed. It will saw much confusi 

 tnd Mr. Bean's Ms. name, should the : 

 id be identical. 



