[79] ALBATROSS EXPLORATIONS. .^81 



whorl, smootli, with the exception of a distinct median keel on the two 

 lower whorls. Sculpture consists of about seventeen very thin, slightly 

 raised, strongly recurved riblets extending from suture to suture, ren- 

 dered nodulous by the intersection of a rather broad, smooth, rounded 

 median carina. The greatest curvature of the transverse riblets is 

 above the carina on the wide, slightly concave subsutural band, which 

 is crossed also by the lines of growth, and in some specimers by nu- 

 merous microscopic revolving strise. On the body-whorl, from the pos- 

 terior end of the aperture to the end of the canal, there are about twelve 

 rather fine, smooth, rounded cinguli ; the first, situated just above the 

 suture and a little wider and more prominent than the others, is ren- 

 dered nodulous by the crossing of the transverse riblets, at which they 

 abruptly end, and is separated from the second by a rather wide, smooth, 

 space, crossed only by the microscopic lines of growth; the space be- 

 tween the others decreases so that, on the canal, they are rather close 

 together. On some of the specimens, there is an additional cingulus 

 midway between the carina and the first cingulus; and three or four 

 of the transverse riblets, and sometimes all of them, on the dorsal sur- 

 face, extend as nearly straight lines to the base of the canal. The ap- 

 erture, in immature specimens, is rather broad-ovate, with a thin,^ 

 slightly curved outer lip, having a very shallow, wide posterior sinus, 

 and the columella has a slight sigmoid curvature, most decided at its 

 posterior third, while in more mature specimens the aperture is very 

 narrow-oblong, with a very much thickened outer lip, forming a con- 

 spicuous white varix with a thin brown edge bending in and partlj' 

 closing the aperture, and with a deep, narrow, oblique sinus considera- 

 bly below the suture. Some specimens have about four smooth, raised^ 

 rounded, revolving threads on the interior of the aperture, which form, 

 by their abrupt terminations, conspicuous nodules within the margin of 

 the outer lip. The outer lip also increases posteriorly and joins the 

 inner lip a little below the suture, thus considerably shortening the 

 aperture. Columella nearlj^ straight, with a row of from four to six 

 very minute white crenulations just within the thin free edge of the in- 

 ner lip ; canal very short, narrow at its base, but suddenly widened by 

 the abrupt outward turning of the lip. 



Color of fresh specimens, when dry, amber, with lighter tinted carina, 

 and red-brown edged aperture ; some specimens are also irregularly 

 spotted with red-brown. 



Length of a medium-sized mature specimen, 5"™ ; its breadth, 2°^"^ ; 

 length of aperture, l.TS^^'^ ; its breadth, .S™'". A specimen without the 

 thickened lip has an aperture 2°^™ long and nearly 1™°^ broad. 



Found in large numbers, both living and dead. 



Mr. W. H. Dall considers this shell identical with a species from 

 Florida to which he has given the name, melanitica (MSS.), but admits 

 a varietal difference. 



