92 



tlie aperture, so as to form a canal behind it : umbilicus very small, 

 but extending through the truncate apex. 



Operculum with the spiral lamella dilated and reflected so as to 

 leave only a very narrow channel between its whorls. 



A fine perfect specimen, loaned to me by Mr. Cuming, has enabled 

 me to describe the operculum and the color of the shell. 



Mean divergence about 50°; length .615 inch; greatest breadth 

 .5 inch ; least breadth .33 inch. 



Cyclostoma Shepardianum. Shell long ovate-conic : color 

 very various, from horn color to reddish brown or slate color, with 

 paler and darker lines alternating, with the lip red or yellowish white : 

 with very closely set fine raised lines, which are traversed and par- 

 tially interrupted by numerous finely waved or zigzag spiral strige ; 

 ' with the upper ends of the transverse lines somewhat fascicled : spire 

 long, with the outlines a little curvilinear : apex truncate, with the 



loss of whorls : remaining whorls five to five and one-half, very 



convex, with a deep suture ; the last whorl detached at its extremity 

 from the penult whorl: aperture ovate-orbicular: inner peritreme 

 moderately produced ; outer peritreme moderately expanded, auricu- 

 4ate above, almost wanting on the left side : umbilicus very narrow, 

 extending through the truncate apex. 



Greatest breadth. Least breadth. 



No. 1. 35° .35 inch. .25 inch. .2 inch. 



.31 .225 



.31 .26 



.26 .225 «► 



.18 .13 



.22 .17 



The variations in color, in sculpture, in the degree of detachment 

 of the last whorl, in ibrm and in size, are remarkable. The vai-ieties 

 of coloripg are sufficiently described above : those of sculpture de- 

 pend on the occasional presence of delicate varices and the develop- 

 ment of the spiral strife, which are coarse or fine or scarcely percep- 

 tible : the distance of the aperture from the penult whorl varies from 

 one-fifth to one-half of the diameter of the aperture. 



Cyclostoma papyuaceum. Shell much elongated, ovate-conic : 

 ■with dark brown irregular transverse bands, which are deeply and 

 sharply undulated on the posterior side, and which are sometimes con- 

 tracted into waving lines, on a ground of pale brown : thin ; elegant- 

 ly" sculptured with very regular crowded striae ; with the intervening 



