328 bulletin: museum of compabative zoology. 



at the periphery and are represented on the rounded base by still fainter traces 

 but without radial sculpture except incremental lines ; 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 aud multisprral, 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 mauuer 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. 



TJ. 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 

 diflferences. 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 no^ a typical 

 Architectonica. 



Choristidae. 

 CHORISTES Carpexter. 



Choristes Carpenter, Canadian Nat., 1872, 6, p. 302 ; type, C. elegant Cpr, op. cit., 

 pi. 7. fig. 13 ; Verrill, Trans. Conn. Acad. Sci., 1882, 5, p. 5il. 



Choristes caxpenteri Dall. 



Plate 3, figure 4. 

 Choristes carpenteri DaW, Proc. U. S. Nat. Mus., 1896, 18, p. 10. 



Shell large, solid, of tliree and a half rounded whorls, white, covered with a 

 pale olivaceous epidermis, sculptured only with somewliat 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 lip 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. S. "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 iu 1471 fathoms, oore, bottom 

 temperature Sfi^.fi 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. 



