Occasional Papers of the Museum of Zoology 79 



the hairs. On the other hand, the shape of these two forms is 

 closer to that of Thysanophora vanattai (see below). 



The sculpture of all of these species is somewhat similar to 

 that in T. fuscula (C. B. Adams), T. proxima Pilsbry, and 

 T. canalis Pilsbry (c/. 1922; Oce. Papers Mus. Zool. Univ. 

 Mich., no. 106, p. 56), but the subdiscoid shape of crinita and 

 arubana is more like that of the generic type, T. cons pur cat ella 

 (Mo relet). The haphazard distribution of the long hairs is 

 very peculiar, but these are only present in the young shells 

 of aruhana. 



Thysanophora vanattai, new species 



Type locality: (A4a) at base of northern escarpment, Seroe 

 Canashito, Aruba. 



Distribution : Aruba ; Baranca Alto ( A2c ; very rare, 1 speci- 

 men), Rooi Frances (A3; quite infrequent, 33 specimens), 

 Seroe Canashito (A4; quite rare, 22 specimens). Under lime- 

 stone rocks, in protected places. 



Shell (fig. xv-57) : small, depressed turbinate, thin and 

 translucent ; very light horn-colored, almost white ; epidermis 

 thin, but usually incrusted heavily with reddish material and 

 even small particles from the surrounding rocks. Whorls: 

 434, quite evenly rounded; very gradually increasing; suture 

 well impressed; last whorl very slightly descending. Sculp- 

 ture of last whorl : rounded growth-wrinkles, separated by fine, 

 impressed lines ; crossed by more oblique striae, which are very 

 weak and short. Embryonic whorls : 1^/2 ; practically smooth, 

 although with extremely minute, irregular punctations, 

 which have a slight tendency towards spiral arrangement. 

 Umbilicus : open, circular ; about 14 the major diameter of the 

 shell. Aperture: slightly oblique, broadly elliptical. Peri- 

 stome : incomplete, simple and sharp. 



Radula (fig. xiv-50) : C/3, L6/2, M2/3 + (4/4+) +1/1; 

 or 10-6-1-6-10. Central : symmetrical, with rather slender, 

 sharp cusps. First lateral: similar but as^Tnmetrical, with 

 entocone lacking ; on the inner side of the mesocone is a narrow 



