ART. 18 SMALL SHELLS DREDGED BY ' ' ALBATEOSS ^' BALL 97 



deep; axial sculpture of (on the last whorl about 16) uniform vertical 

 threads with subequal interspaces; the spiral sculpture consists of 

 an undulate thread at the suture, and another at the margin of the 

 base, and two stronger ones near the periphery; the intersections are 

 not nodose; the reticulations are deep and square, the base is flattish 

 with only flexuous incremental lines inside the marginal thread. 

 Length, 7; diameter, 1.8 mm. U. S. Nat. Mus. Cat. No. 329358. 



Off Georgia, eight specimens. 



This is the only species of typical Cerithiopsis obtained from these 

 dredgings, unless C. eliza be considered one. 



Judging from its smooth styliform nucleus, the type of Triforis 

 Deshayes (T. ylicata) belongs in this family and not in the group to 

 which Triphora Blainville is referred. 



Subgenus Laskeya Iredale 



Eumeta Morch, Faunula Moll. Islandiae, Vid. Medd., p. 208, 1868; sole 

 example Turrilella costulata Moller = Eumeta arctica Morch. Not 

 Eumeta Walker, 1855, Lepidoptera. 



Laskeya Iredale, Proc. Mai. Soc. London, vol. 13, p. 30, Aug., 1918. 



This subgenus is characterized conchologically by its short blunt 

 nucleus, as compared with the styliform nucleus of typical Cerithiopsis, 

 and its strong axial ribbing. Fischer adds that the cusps of the uncini 

 are finely denticulate. 



The nucleus of the typical species is small and smooth, not exceed- 

 ing one and a half whorls, and the succeeding nepionic whorl has 

 extremely fine hair-like axial ribbing, followed by the adult sculpture. 



The deep water forms described in this paper have a swollen 

 nucleus, usually of greater diameter than the succeeding nepionic 

 whorl, and the latter is usually axially ribbed, with or without spiral 

 lines. While this peculiar nucleus is in my opinion the result of its 

 deep-water environment (found in a great variety of genera from 

 deep water) it seems not to occur in all the deep water Cerithiopsides, 

 some of which retain the styliform nucleus, so it seems tentatively 

 advisable to gather the groups with the swollen nuclei into a special 

 section. 



Section ONCHODIA Dall, 1924 



LASKEYA (ONCKODIA) BENTHICA Dall « 



Shell glassy white, with one swollen smooth nuclear whorl followed 

 by one nepionic whorl with retractively angular small riblets with 

 very fine spiral striae in the interspaces, succeeded by seven whorls with 

 the adult sculpture; suture distinct, appressed, slightly constricted; 

 axial sculpture of (on the last whorl 14) stout low, rounded ribs with 



<See Proc. Biol. Soe. Wash., vol. 37, p. 89, Feb. 21, 1921. The present species is the type of thesection. 

 24105— 27t 7 



