328 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
at the periphery and are represented on the rounded base by still fainter traces 
but without radial sculpture except incremental lies; umbilicus in width to the 
whorl near the aperture as 2.5 to 4.0; margin of the umbilicus with a double 
row of beads on the earlier whorls (visible inside the umbilicus), but on the last 
whorl all that remain are about ten very short radial ridges ; verge of the umbili- 
cus only feebly angular; aperture rounded, peritreme simple, sharp, continuous ; 
operculum externally flat and multispiral, the edges of its whorls slightly over- 
lapping; inner face with a central prominence, formed by the opercular layers 
being coiled loosely upon each in the manner of a paper “ spill.” Max. diam. of 
shell, 9.2; min. diam. 7.5; diam. of aperture, horizontally, 4.3; height of spire, 
4.7 mm. 
U.S. S. “ Albatross,” station 3392, in 1270 fathoms, hard bottom, tempera- 
ture 36°.4 F., in the Gulf of Panama. 
This is an interesting species notwithstanding its poor condition, having an 
easily recognizable sculpture, unlike that of any other known. The operculum 
is peculiar and apparently related to that of Torinia, but the opercula of all this 
family seem to be constructed on the same plan, notwithstanding superficial 
differences. I prefer not to attempt to refer this species to its subdivision of the 
genus without better material, though it is obvious that it is not a typical 
Architectonica. 
Choristidae. 
CHORISTES Carpenter. 
Choristes Carpenter, Canadian Nat., 1872, 6, p. 892; type, C. elegans Cpr., op. cit., 
pl. 7. fig. 18; Verrill, Trans. Conn. Acad. Sci., 1882, 5, p. 541. 
Choristes carpenteri Datt. 
Plate 3, figure 4. 
Choristes carpentert Dall, Proc. U. S. Nat. Mus., 1896, 18, p. 10. 
Shell large, solid, of three and a half rounded whorls, white, covered with a 
pale olivaceous epidermis, sculptured only with somewhat irregular, rude, incre- 
mental lines; suture deep, the whorl in front of it slightly excavated; base 
rounded, the umbilicus narrow, deep; aperture subovate, not interrupted by the 
body; the inner hp nearly straight, the outer lip simple, sharp-edged; the 
interior of the aperture white. Height (somewhat eroded), 21; height of aper- 
ture, 14; diameter, 21 mm. 
U.S. 8. “Albatross,” station 3382, Gulf of Panama, in 1793 fathoms, mud; 
bottom temperature 35°.8 F. U.S. N. Mus. 123,039. 
Another specimen was dredged at station 3361 in 1471 fathoms, ooze, bottom 
temperature 36°.6 F. and a defective individual at station 3415, off the Mexican 
coast in Lat. 14° 46’ N., in 1879 fathoms, ooze, bottom temperature 36° F. 
