BALL: MOLLUSCA. AND BRACHIOPODA. 351 



suture ; these are crossed by subequal, fine, sharp, somewhat protractive axial 

 threads, at first small and crowded, but becoming more distant, subequidistaut, and 

 sharp as the wliorl grows ; the spirals increase by intercalation, and on the second 

 whorl the axial threads begin to fade out, until they are reduced to headings on 

 the spirals between the suture and shoulder, and finally on the last whorl the 

 spiral next the suture alone is beaded, and the peripheral major spirals have in- 

 creased to six, wliile on the sliglitly flattened base there are about eighteen, close- 

 set, even, gradually diminishing in size toward the umbilicus, which is bordered by 

 a small sulcus, inside of wiiich is a square-topped keel of two threads notching the 

 margin of the aperture where they intersect it ; inside of this is a twisted funic- 

 ular umbiUcus with one entering spiral thread on its walls, also ending in a 

 small notch at the aperture ; mouth rounded except at the notches ; outer lip 

 sharp, thin, crenulated by the spirals ; pillar thiu, arcuate, slightly reflected ; 

 whorls rounded except where sliglitly turrited by the shoulder keel ; operculum 

 thin, brownish, concave, many whorled, the margins of the whorls projecting as 

 laminae from the surface externally. Alt. of shell, 17; of last whorl, 13 ; of ap- 

 erture, 8.5 ; max. diam. 15.5 ; min. diam. of base, 13.5 mm. 



tJ. S. S. "Albatross," station 3413, near the Galapagos Islands, in 1360 fath- 

 oms, ooze, bottom temperature 36°F. U. S. N. Mus. 122,959. 



Tills elegant little shell is well distinguished by its sculpture from any of the 

 allied species. It is perhaps not quite mature, and the pillar lip in the fully adult 

 shell may be somewhat modified. 



Solariella equatorialis Dall, n. sp. 



Plate 5, figure 11. 



Shell thin, pearly, the nacre shining througli (he translucent outer coating, and 

 a pale yellowisli, axially striated, silky periostracum ; whorls six, exclusive of the 

 (lost) nucleus ; suture distinct, not channelled ; whorl in front of it horizontal 

 with a fine spiral thread at a short distance, giving a somewhat tabulate efl"ect ; 

 somewhat more distant is a second stronger thread at the shoulder, and a similar 

 one at the peri|)liery, while a fourth forms the margin of the base against which 

 tlie suture is laid ; on the base are four more similar threads, becoming gradually 

 more adjacent and feebly beaded or nearly simple, except the fourth, which is dis- 

 tinctly, minutely beaded, while a fifth, forming the brink of the large, wide, and 

 deep umbilicus, is even more strongly beaded; axial sculpture of minute, feeble, 

 radial wrinkles which at their intersection with the posterior thread crenulate it, 

 and on the second and third threads produce, at intervals of about a millimeter, 

 sharp, triangular, sulispinose nodules ; the entire shell is covered with axial, fine, 

 retractive, silky striatimi; whorls full, base rounded; umbilicus very deep, funic- 

 ular, the walls axially striated; aperture rounded-quadrate, the margius thin; 

 pillar oblique, slightly excavated, not callous, slightly expanded ; body and throal 

 pearly. Alt. 21 ; of last whorl, 14; of aperture, S.5; max. diam. of shell, 19.5 ; 

 of umbilicus. 5.5 mm. 



