326 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY, 



umbilicus imperforate ; axial sculpture of very minute elevated, arcuate, radial 

 lines, in harmony with the lines of growtli which minutely but distinctly bead the 

 keel nearest the suture, but do not affect the others ; aperture subquadrate, outer 

 lip modified by the sculpture, tliin, coucavely arcuate beliind ; body with a thiu 

 wash of callus ; pillar thiu, coucave, strongly twisted, not reflected, truncate 

 anteriorly, so that its junction shows a projecting point in front of a shallow sul- 

 cus. Lon. of sliell, 4.0; of aperture, 1.5.; max. diam. 3.5 mm. 



U. S. S. " Albatross," station 3431, off Mazatlan, in 995 fathoms, mud, bottom 

 temperature 37° F. U. S. N. Mus. 123,034. 



This species is easily distinguished from the preceding by the different sculp- 

 ture, its more elevated form, and the absence of the umbilical perforation. It is 

 nearest among described species to the monocingulata of Seguenza, from which it 

 may be instantly distinguished by the beaded aute-sutural keel and its somewhat 

 broader and shorter conical form. 



Vermetidae. 



PETAtOCONCHUS Lea. 



Petaloconchus complicatus Dall, n. sp. 



Coil at first closely wound and more or less obliquely bent in conformity with 

 its situs, the first few turns with a subcircular section, very irregularly disposed, 

 those following with a roughly hexagonal section closely coiled arouud a barely 

 perforate axis, closely coherent to each other and runniug up to twenty or more 

 in number, after which the tube once more becomes erect, with a circular 

 section, and a slight dextral twist ; aperture circular, often with a series of in- 

 ternal concentric lamellae as if the animal had attempted to contract the opening 

 by secreting a succession of smaller tubes within it; sculpture irregular; apart 

 from incremental lines, there is a longitudinal, irregular, but tolerably smooth ridge 

 on the middle of the exposed whorl with strong wrinkles at right angles to it on 

 each side but not crossing it. At resting stages there are sometimes angular pro- 

 jections of the margin of the temporary aperture; the wrinkles are sometimes 

 reticulated by longitudinal subequal threads, which may be entirely wanting on 

 other parts of the same individual; the erect portion is nearly smooth except for 

 lines of growth ; the color is a pale ferruginous brown ; the length of the coiled 

 portion may be about 16, and of the erect part 27 mm., tlie tube with a diameter 

 at the aperture of 2.3 mm. There is one internal basal lamella and a smaller one 

 projecting from the axial wall at about right angles to and a little above the 

 former. 



U. S. S. " Albatross," station 3368, near Cocos Island, on dead shells, at a 

 depth of 66 fathoms, bottom temperature 5S°.4 F. U. S. N. Mus. 123.035. 



This has somewliat the habit of the ty|iical species of the genus, but is smaller, 

 less regular, and with a much smaller axial perforation. 



