84 University of Michigan 



C15 and CI 7a, lots mixed. Frequent. Shells rather solid, with heavy 

 peristomal callus. Coloration diffuse, to dark and sharply marked. 



C16. Frequent. Shells solid with heavy callus. One specimen has the 

 heaviest callus in the sets; the shell is 2 mm. thick on the palatal wall. 

 Dark bands and varices. 



Cbl6, 17. Rare to infrequent; occurs in the richer valleys throughout 

 the region of older rocks from Campo Sint Kruis to the Tafelberg of Sint 

 Hyronimus. Quite heavy, with diffuse markings. 



C20. Infrequent. Similar to Cbl7. 



A2c. Very rare; only found on Cereus in Rooi Taki. Thin and dull- 

 colored. 



A4a. Eare; on trees at base of northern escarpment. Similar to A2c. 



B3-7; Bb3, 7. Rare to frequent. In the richer localities, both over 

 limestone and in the interior region. The largest shells collected; solid 

 with heavy peristomal callus. Usually rather dull colored. 



B8. Quite infrequent. Somewhat smaller than the preceding. 



From the comparison of dimensions (Table VIII), it will be 

 seen that typical D. virgulatus, as judged by the figures, is a 

 considerably more slender shell than that represented by the 

 mean of the Curagao specimens, and, in fact, corresponds to 

 the most slender shells from the Dutch Leeward Islands. It 

 would be interesting to compare a large lot from Porto Rico. 



The radular formula (fig. xiv-52) of a specimen from Seroe 

 Papaja (Cllc) is: 86-1-86. The central is asymmetrical and 

 tricuspid. Almost all of the laterals are also tricuspid, but, 

 as is usual in the genus, the ectocone is very variable and may 

 be entire and bifid in two consecutive teeth; as a rule, the 

 outer teeth are more variable than the inner, but the first 

 lateral itself may be 4-cusped, while the 83rd tooth is com- 

 monly tricuspid. The transverse rows run obliquely back- 

 wards to the 54th tooth, which is peculiarly elongate and lacks 

 the entocone ; with the 55th, the rows curve abruptly forward so 

 that the entire row has the shape of a broad W (see line under 

 scale in figure ) . In the 1st to the 53rd teeth, the entocone is 

 markedly larger than the ectocone and is quite widely separated 

 from the mesocone, but the teeth beyond the 54th are more 

 nearly symmetrical. In addition, the bases, in each portion, 

 are almost parallel to the direction of the row, so the teeth of 

 the outer and inner limbs are quite markedly different in ap- 



