120 MACROCERAMUS, HAITI. 



bb. Shell wider, diam. less than one- third the 

 length. M. r. sublineatus, no. 5&. 



III. Base marked with radial streaks, crossed by median and 

 subperipheral bands ; apex blackish or blue-black. 



a. Oblong-ovate, the outlines of spire very convex; 

 upper surface of whorls marked with brown spots 

 in obliquely longitudinal rows, about 3 spots in a 

 row, sometimes united by lines, chain-like. 



M. formosus, no. 8. 



aa. Convexly conic, the outlines slightly convex; 

 marked with oblique rows of chestnut spots, 3-4 

 spots in a row. About 18 x 8 mm. 



M. dominicensis, no. 7. 

 aaa. Spire with almost straight lateral outlines. 



b. Small spots upon oblique streaks. Sculp- 

 tured with rather fine, low rib-striae 

 throughout. About 16-19 x 5.5 mm. 



M. tenuiplicatus, no. 9. 



bb. Marked with spiral brown lines crossing 

 streaks ; sculpture of rather coarse, low rib- 

 striae. M. t. swiftianus, no. 9a. 



IV. Base with a subperipheral band and umbilical patch (one 

 or both rarely wanting), but not distinctly streaked 

 radially. 



a. Shell cylindrical below, the upper third or half 

 tapering and conic ; base very convex ; suture more 

 or less crenulate. 



b. White, dotted and irregularly marbled with 

 corneous ; irregularly, coarsely, obtusely stri- 

 ate ; suture crenulate ; 10-11 x 3.3-3.7 mm., 

 whorls 10-11. Santo Domingo. 



M. hermanni, no. 16. 



bb. Cream or brown- tinted, copiously streaked 

 with brown; finely and closely sculptured 

 with thread-like striae ; 11 x 4 to 15 x 4-4.5 

 mm., with 9%-12% whorls. S. Domingo. 



M. subcylindricus, no. 17. 



aa. Shell regularly or somewhat cylindrically taper- 

 ing; suture even. 



