592 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 45. 



MARGARITES SIMBLUS, new species. 



Shell pale gray, beehive-shaped, with a blunt apex and five and a 

 half rapidly enlarging convex whorls; nucleus minute; subsequent 

 whorls pohshed, finely spirally striate, crossed by very fine flexuous 

 striae corresponding to the fines of growth, wliich more or less micro- 

 scopically crenulate the interspaces between the spirals; suture not 

 impressed; base with an obscure angulation peripherally, the sculp- 

 ture similar to the rest of the shell but more pronounced; umbificus 

 narrow, deep; aperture subquadrate, obfique; the piUar thin, white; 

 the throat pearly. Height of shell, 13; of last whorl, 10; maximum 

 diameter of base, 14 mm. 



Dredged in deep water, off Santa Barbara Channel, Cafifornia. 

 Cat. No. 267172, U.S.N.M. The specimen did not contain the animal 

 or operculum. 



CALLIOSTOMA NEPHELOIDE, new species. 



Shell acute-conical, trochiform, of about nine whorls, yellowish, 

 with radiating dark-purple nebulosities and flammules; nucleus more 

 or less inverted, white, glassy, minute; a nepionic whorl and a half 

 follows, with three spiral, latterly beaded cords ; the remaining sculp- 

 ture comprises a strong prominently beaded cord at the periphery 

 immediately in front of which the suture is laid; on the last whorl, 

 between the periphery and the suture behind it, are about a dozen 

 threads smaller than that at the periphery but equally and uniformly 

 beaded, with subequal, smooth interspaces, and mostly alternating 

 in size; there is no obvious axial sculpture; base bordered by a cord 

 (without beading) of the middle size, between which and the center 

 of the base are 18 to 20 flattish straplike spirals, faintly irregularly 

 undulated and with subequal or narrower interspaces, except the 

 three or four nearest the columella which are larger, more distant^ 

 and with more or less obscure nodulation; base only slightly convex; 

 pillar arcuate, white, with an obscure ridge around the imperforate 

 umbilical region, ending at the anterior end of the pillar in a nodulous 

 swelling. Aperture broken, but evidently subquadrate with thin, 

 simple, outer lip. Height of shell, 25; of last whorl, 15; maximum 

 diameter of base, 22 mm. 



Station 2804, Panama Bay, in 47 fathoms, muddy bottom. Cat. No. 

 96637, U.S.N.M. 



This species is represented only by one broken specimen, but when 

 perfect must be one of the most elegant of the West American species 

 of this elegant group, and quite distinct from any of the others. 



PECTEN (PSEUDAMUSIUM) ARCES, new species. 



Shell hyaline white, with no anterior ear, subcircular, slightly con- 

 vex; hinge Ime rather long, ligament and pit very small, entire surface 

 of convex valve sculptured with subequal radial threads and similar 



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