THE NAUTILUS. 75 



calling what de Folin and Carpenter say in regard to the extreme 

 variability of what are supposed to be species, I judge it better 

 not to encumber the synonymy by creating new names. 



Caecum annulatum Brown. PI. V, Fig. 1. 



A single specimen in the collection resembles the figure given 

 by Try on. At first sight it suggests pulchellum but enlarges 

 more rapidly towards the aperture. It differs also in having 

 three or four large costae next to the margin or lip. 



Caecum cooperii Smith. PI. V, Fig. 2. 



This species was discovered by Sanderson Smith in Gardiner's 

 Bay at the end of Long Island in five fathoms. This is a very 

 distinct form. From one specimen which was white and chalky 

 and resembled a dead shell I obtained the operculum which 

 was orbicular, thick, brown in color, concave with six sharp 

 revolving ribs, sinistral in direction, indicating that the shell 

 was dextral. In various references to the operculum of Caecidae 

 no mention is made of the direction of the revolving striae. 



Stimpson in his "Shells of New England " figures accurately 

 the operculum of Caecum pulchellum, showing the sinistral spiral 

 of the lines of growth, yet makes no reference to its significance. 

 Even Carpenter in his monograph while describing a number of 

 opercula of different species makes no mention of the direction 

 of the striae. He describes the shape of the operculum, 

 whether flat, convex or concave, whether thick or thin, the 

 color, etc., but not a word is given as to whether the spiral 

 lines are dextral or sinistral. In his examination he used a 

 ^in. obj. and the direction of the lines must have been very 

 plain. With the lowest power of Zeiss the direction of the 

 spiral was easily detected. 



Caecum johnsoni Winkley. PI. V, Fig. 3. 



This was first discovered at Woods Hole. The drawing is 

 made from a co-type in the collection of the Boston Society of 

 Natural History. I am indebted to Mr. C. W. Johnson for 

 the loan of it and for other kindnesses. The septum is sub- 

 ungulate and has transverse lines of growth. It resembles the 

 figure in Tryon of C. achirona of de Folin. 



