BALL: MOLLUSCA AND BRACHIOPODA. 663 



a single sharp sulcus at the extreme margin, running between two slightly ele- 

 vated lamellae. Alt. of type specimen, 22 ; of aperture, 17 ; max. diam. 16.5 mm. 

 A larger specimen is 23.5 by 20 mm. 



U. S. S. " Albatross," stations 2799, 2800, 2801, 2803, 2804, iu the Bay of 

 Panama, iu 7 to 47 fathoms, mud ; also, dead specimens, at stations 3354 and 

 3392, in 322 to 1270 fathoms, muddy bottom. U. S. N. Mus. (types) 46,446. 



The young shell has darker, faint brownish streaks obscurely disposed in two or 

 three spiral bands. The adult is without perceptible pattern. The shell belongs 

 to the group of "maroccana," under which so many distinct forms have been 

 lumped by undiscriminatiug authors, and is perhaps nearest to some varieties of 

 the West Indian N. livida Philippi, which has a differently sculptured operculum. 



Natica (Cochlis) scethra Dall, n. sp. 



Plate 11, figure 5. 



Shell small, moderately elevated, with about three whorls, exclusive of a smooth, 

 polished nucleus of two and a half whorls, which changes abruptly into the adult 

 sculpture; suture distinct; color pale brown with three obscure pale bands, one 

 about the region of the shoulder, another a little in front of the periphery, and 

 the third, less distinct, on the base; all rather ill defined; whorls smooth, except 

 between the shoulder and the suture, where start numerous (on the last whorl 

 twejity-six), sharp, very obliquely retractive, narrow wrinkles ; aperture ovate, 

 outer lip arcuate, thin, simple, sharp ; body with a well-marked callus, terminat- 

 ing at a notch at the posterier end of the umbilicus ; at the pillar is a pad, formed 

 by the end of a flattish ridge, which winds into the depths of the umbilicus, 

 leaving a narrow chink to the left of the pad; anterior lip slightly thickened ; 

 operculum flat, white, with brownish clouding, a small patch of roughened callus 

 obscuring the spiral part externally ; outer edge elevated, with two deep, very 

 narrow sulci revolving within it, the interspace forming a single flat-topped rib. 

 Height of shell, 17-0 ; of last whorl, 15.5 ; of aperture, 11.5 ; max. diam. 16.0 mm. 



U. S. S. " Albatross," station 3391, Gulf of Pauama, iu 153 fathoms, mud, 

 bottom temperature 55°.8 F. U. S. N. Mus. 123.048. 



POUNICES MONTFORT. 



Uber (Anonymous) Mus. Calonn., 1707, p. 21. 



Alhula Bolten, Mus. Bolt., 1798, p. 20 ; not Alhula Gronovius, 1763. 



Polinices Montfort, Conch. Syst., 1810, 2, p. 223; type, Nerita mamilla Linn^. 



> Neverita llisso, Hist. Nat. Eur. Me'r., 1826, 4, p. 147 ; type, N. Josephinne Risso. 



> Euspira Agassiz, in Sowerby, Min. Conch., 18-12, German eil., p. 14. First spe- 



cies, N. glaucinoides Sowerby, = A^ labellata Lamarck, 1804. 



> Lunatia Gray, P. Z. S. Lond., 1847, p. 149 ; type, N. ampullaria Lamarck 



( = Euspira Ag.). 



