206 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



Odostomia (Ghrysallida) swetti Strong & Hertlein, new species 



Plate 18, Fig. 11 



Shell minute, elongate-ovate, white; nuclear whorls deeply obliquely 

 immersed in the first postnuclear whorl; postnuclear whorls 5, slightly 

 rounded, sutures channeled; axial sculpture of nearly vertical ribs of 

 which 16 appear on the second, 22 on the third, and 26 on the penulti- 

 mate whorl ; spiral sculpture of 4 cords of which the upper 3 are ren- 

 dered nodulous by the intersection with the axial ribs, while the lower 

 cord is smooth or feebly waved at the termination of the axial ribs; 

 the spaces inclosed by the axial ribs and spiral cords form well-impressed 

 squarish pits; periphery of last whorl marked by a strong groove; base 

 rather long, rounded, marked with 6 spiral cords which become weaker 

 and closer spaced toward the umbilical region; aperture oval, outer lip 

 thin, flattened in the middle; columella strong, curved, provided with a 

 slender fold at its intersection; body with a moderate callus. The type 

 measures: length, 2.1 mm; diameter, 1.2 mm. 



Holotype: No. 738 (Calif. Acad. Sci. Paleo. Type Coll.), from 

 Loc. 27,228 (C.A.S.), dredged in from 3 to 9 fms. off Taboga Island, 

 Panama. L. G. Hertlein collector. Thirty additional specimens were 

 dredged at the same locality. Seven young specimens collected on the 

 rocks at Loc. 27,257 (C.A.S.), at Panama City, seem to belong to this 

 species. 



In the key given by Dall and Bartsch to the west coast species in 

 the subgenus Ghrysallida,^^ this would be grouped with vincta from San 

 Pedro, California, and fasciata from Mazatlan, Mexico. It differs from 

 both in the more oval shape and more nearly vertical ribs, as well as in 

 other details. 



This species is named for Mr. Charles Swett, chief officer of the 

 motor cruiser Velero III during the expedition on which the present 

 collection was made. 



Odostomia (Pyrgulina) marginata C. B. Adams 

 Plate 18, Fig. 13 



Chemnitzia marginata C. B. Adams, Ann. Lyceum Nat. Hist. New 

 York, vol. 5, 1852, pp. 391-392, 536. 'Tanama." 



40 Dall, W. H., and Bartsch, P., U. S. Nat. Mus., Bull. 68, 1909, pp. 137, 

 138. 



