364 PROCEEDINGS OF THE ACADEMY OF [Nov., 



Dinia compitorum n. sp. Fig\ire 3. 



The shell is white, oblong, perforate, rounded below, truncate and 

 imperforate at the summit. The surface has faint traces of spiral 

 striae, and at the base there are several distinct spirals. The Up 

 is inserted in the center above, rising but little; outer lip is quite 



Fig. 3. — Dinia compitorum n. sp. 



slightly curved, and in adults is rather strongly thickened within. 

 In profile view it recedes decidedly above, very little at the base, 

 and curves forward very slightly elsewhere. The columella pro- 

 jects obliquely towards the right and is abruptly truncate at base. 



Length 7.1, diameter 4 mm. 



Oahu: Honolulu, type locality and Haleiwa (Pilsbry, 1913); 

 Paumalu and Mokapu Point (Bryan). Maui: off Mala Bay, 

 near Lahaina in 25 to 75 feet. (Thaanum and Langford). 



Dinia has been considered a subgenus of Atys but it differs by 

 lacking a spiral fold in the lip ascending from the summit, and by 

 the very strong truncation of the columella, characters sufficient 

 for generic separation. There are now four Indo-Pacific species. 



ATYS. 



Five of the six species of Atys now known from the Islands were 

 figured in the first paper of this series, 1917, pp. 216-218. A fossil 

 (Pleistocene?) species, probably extinct, is now added. 



Key to the Hawaiian species of Atys. 



1. Columella rather thin, mainly vertical or weakly sigmoid, the 



edge but narrowly reflected {Atys proper) 2 



Columella thicker, its edge reflected, bounded by an arcuate 

 groove (Subgenus AUculastrum Pils.) 3 



2. Diameter about two-thirds of the length; rather inflated, often 



striped; 15.5 x 10 mm A. kuhnsi Pils. 



Smaller, less inflated, white A. semistriata Pse. 



