628 PROCEEDINGS OF THE ACADEMY OF [DeO., 



Streptaxis deplanchei Drouet. 



Streptaxis deplanchei Drouet, Moll. Guyane Fran^., 56, t. q., figs. 6-9. 

 Conchylien Cabinet, Streptaxis, XXXIII, p. 15. Man. Conch. (2), I, p. 79, 

 pi. 16, figs. 80-82. 



About eighty specimens were taken at Ceara-Mirim and two 

 specimens, "from the Coast region of the State of Ceara, " were sent 

 by Mr. Rocha. 



streptaxis deplanchei quixadaensis n. subsp. 



A single specimen was taken about a mile below Quixada which 

 differs from the type in being a little larger (diam. 7 mm.), with only 

 a perceptible trace of the inner parietal nodule; a half-grown speci- 

 men taken in the same locality is probably of the same subspecies. 



Streptaxis cookeana n. sp. PI. XXII, figs. .5, 6, 7. 



Shell depressed, with low, conoidal spire with the lateral outlines but 

 slightly convex, perforate, the umbilicus about .5 mm. in diameter, 

 twisted so as to appear closed above the last whorl, but actually 

 extending to the apex; thin, pellucid, glossy, very faintly yellowish; 

 the first If nepionic whorls nearly smooth, the rest closely, irregularly, 

 and finely costulate, the costulae slightly arcuate and strongly retract- 

 ive, about as wide as the interspaces, in places indistinct, but 

 showing about 13 to the millimeter on the penultimate whorl; 

 costulae obsolete on the base except at the mouth of the umbilicus 

 where they are intensified rather abruptly, forming about twelve 

 vertical ribs which extend inward over nearly the whole of the last 

 whorl. Whorls 5|, increasing regularly in width for 4^ whorls, when, 

 the apparent width is modified by the characteristic distortion of 

 the genus; sutures distinct, almost impressed. Aperture slightly 

 broader than high, very roundly triangular ; peristome moderately 

 expanded, slightly recurved over the umbilicus, white; parietal 

 wall covered by a thin callus uniting the extremities of the outer 

 lip; no apertural teeth present. Young shells perfectly regular, 

 with a wider umbilicus than in the adult and showing frequent 

 varices (one to three to a whorl) on the base, which give the young 

 shells the appearance of Scolodonta and suggest the possibility that 

 some species assigned to Scolodonta may prove to be the young of 

 Streptaxis. 



Alt. 6, greatest diam. 9.75, least diam. 7, width of aperture 3.25, 

 alt. of aperture 3 mm. 



Animal grayish, marked by orange-yellow colored ocular tentacles 

 and a line of the same color extending backward from the base of 

 each tentacle; young and adult animals are the same in color. 



