THE NAUTILUS. Ill 



ture is very fine grained, the suture narrow but deeply plowed, and 

 the columella armed with two or three small denticles at the base, as 

 in the genus generally. The outer lip is weakly grooved within on 

 the thick part near the margin. The deep umbilicus readily sepa- 

 rates this species from the following form. 



The exact date of d'Orbigny's publication of this species is not 

 known to me. 

 Cblorostoma Hldalgol n. sp. 



Shell very similar to Chlorostoma patagonicum Orb., (Trochus cor- 

 rugatus Koch), but wholly imperforate, the umbilical region covered 

 witli a white callus. Fleshy-einereus, with the apex eroded, white. 

 Sculpture of crowded spiral series of small, irregular granules, simi- 

 lar to those of G. patagonicum. Spire conic, periphery rounded, the 

 base flattened. Aperture very oblique, somewhat triangular; colu- 

 mella armed with two small teeth at its junction with the basal lip. 



Alt. 15, diam. 17 mm. 



" Rio Negro, Patagonia," coll. A. N. S. P. 



This form differs conspicuously from C. patagonicum Orb. (corru- 

 gatus Koch) in the completely imperforate axis, the other species 

 being conspicuously umbilicated at all stages of growth. C. Hidalgoi 

 is also more conical. In color, sculpture, and the deeply scored 

 suture, the two species are extremely similar. 



It is named in honor of the author of the Moluscos del Viaje al 

 Pacifico, a meritorious work on the South American fauna. 



Chlorostoma Orbignyanum, n. sp. 



Shell imperforate, conic, with flattened base; purplish-gray, with 

 blackish spirals above, black below. Surface dull, sculptured with 

 numerous low spiral lira, several below the suture obscurely beaded, 

 the others nearly smooth; the line near the suture separated by 

 narrow intervals, those toward the periphery more widely spaced, 

 with one or several interstitial threads in each interval. There are 

 about 10 lira? on the penultimate whorl, and 10 below the periphery 

 on the base. Whorls o, very convex, separated by deep sutures, the 

 last whorl flattened below the suture, obtusely angular at the peri- 

 phery ; the base free from spiral sculpture in the center, eroded and 

 brilliantly pearly in front of the aperture. Aperture very oblique, 

 pearly within, with a rather wide dull border within the thin outer 

 lip, acute ; columella short, concave, porcdlanous, terminating in a 

 small tubercle below, adjacent to which there is a minute denticle; 



