218 



PROCEEDINGS OF THE ACADEMY OF 



[June, 



The ascending axis is broad, very obliquely spiral, terminating in a 

 posteriorly projecting point. Anteriorly the axis is very minutely 

 perforate; columella broad, concave, appressed above, obliquely 

 truncate below. 



Length 10.6, diam. 4.8 mm. 



Off Honolulu in 6 to 8 fathoms, D. B. Kuhns. Type No. 117075, 

 A. N. S. P., from No. 397a Thaanum coll. Also Hilo, Hawaii. 



This form agrees with the account and figures of A. debilis except 

 in shape; it is wider in the upper part, though not at the vertex. 

 As no specimen of A. debilis is in the Pease collection at Cambridge, 

 and comparison with the supposed type in London is impracticable 

 at this time, the present form is described subject to further inves- 

 tigation. 



The summit is more pinched up into a narrow ridge than in A. 

 cijlindrica (Helbling) or A. parallela Gld. A. hyalina Watson is less 

 slender. 



The species reaches a size considerably greater than the specimen 

 serving as type. One from Hilo, sent by Mr. Thaanum (No. 117076) 

 measures, length 15, diam. 6.7 mm. There are about 11 spiral 

 grooves on the upper fourth, followed by 4 or 5 slightly elevated 

 spirals, the basal third, below the smooth space, having many spiral 

 grooves, as usual. 



Fig. 6. — Atys costulosa. Fig. 7. — Atys debilis. 



Fig. 8.- 



-Atys cornuta. 



Atys costulosa Pease. Fig. 6. 



1869. Atys costulosa Pse., Amer. Journ. Conch. V, p. 73. 

 1893. Atys costulosa Pse., Pilsbry, Man. Conch. XV, p. 267. 



Waimalu, Oahu; Type No. 31714 Mus. Comp. Zool., Pease coll. 

 This species is quite distinct by the well developed longitudinal 



