MUSEUM OF COMPAKATIVE ZOOLOGY. IGl 



Holmes, of the Carolina Post Pliocene, would seem to he related to it. The 

 sini])lii'ity and eleqance of the scul])ture an; romarkuljle. It is named in honor 

 of Dr. W. II. Rush, U. S. N., who has made praiseworthy collections of shells 

 in the Antillean region. 



Mitra (Costellaria?) trophonia n. s. 



Shell elonj^ated, with a Stilifer-like nucleus of five or more whorls, acute, 

 yellowish hrown, polished, glassy, and about eight other normal moderately 

 rounded whorls ; the last whorl forms more than half the shell ; sculpture 

 of about (on the last whorl) fourteen sharp little-elevated ridges, which are 

 rounder on the earliest whorls and obsolete on the last half of the (adult) last 

 whorl ; incremental lines irregularly prominent ; spiral sculpture of fine faint 

 grooves, most visible between the ridges, three or four ill-defined distant re- 

 volving ridges on the anterior part of the last whorl which make a sort of arch 

 in the transverse ridges when the latter cross them, and two to four ridges 

 on the canal corresponding to the plaits ; siphonal fasciole prominent and 

 well marked ; suture distinct, not deep, waved by the ends of the transverse 

 ridges ; color from pale yellow to deep orange, with a narrow opaque white 

 band a little way behind the suture, which swells a little where it crosses the 

 transverse crests, and may in some specimens be represented by a series of spots 

 on the crests ; surface rather glossy ; aperture narrow, outer lip thin, sharp, 

 with faint fine lirse in the throat ; a small callus at the posterior angle on the 

 body whorl ; plaits four, the first rather small ; canal nearly as wide as the 

 aperture, somewhat recurved. Lon. of adult shell, 20.0; of last whorl, 12.0; 

 of nucleus, 2.0; max. lat. of shell, 6.75 mm. 



Habitat. Station 132, in 115 fms., broken shell, off Frederickstadt, Santa 

 Cruz, bottom temperature GS^.O ; Station 247, off Grenada, in 170 fms., ooze, 

 bottom temperature 53°. 5 F. 



The peculiarly rude aspect resulting from the irregular incremental lines 

 and the sharp-edged transverse ridges is characteristic, and resembles some- 

 what that of certain species of Trophon or Anachis. I have not been able to 

 find in the monographs, or elsewhere, any species which could well be com- 

 pared to this one in sculpture. It is quite possible that its color varies. 



The nearest species to M. trophonia is M. alhocincta C. B. Adams, which is 

 much stouter and stumpier, with wider and rounder transverse ridges, rounder 

 form, and less acute and laterally flattened spire. It is also considerably smaller, 

 with a shorter canal in proportion, and is black in all the specimens I have 

 seen, without exception, and shows no tendency to paler variations. M. trophonia 

 has also a faint distant resemblance to M. Defrancei Payraudeau. 



Mitra (Turris ?) Bairdii Dall. 



. Shell waxen gray or greenish, elongated, acute, with ten or eleven flattened 

 whorls; nucleus? (wanting); sculpture consisting on the earlier whorls of up 

 VOL. xviii. 11 



