REPORT ON THE .GASTEROPODA. 543 



I believe Ccrithium, yracilc, Jeffr., to be identical with this species, Dr. Cfwyn Jeffrey's type speci- 

 mens having been carefully compared with the Challenger shell by both Mr. Edgar A. Smith and 

 myself. The Cerithiclla Wkiteavsii, Verrill (Cat. Mar. Moll. N. Eng, Trans. Conn. Acad., 1882, 

 vol. v. pt. 2, p. 522, pi. xlii. fig 7), a young specimen of which Prof. Verrill kindly sent me, 

 will probably turn out on examination of a considerable number of specimens to be the same 

 species. 



6. Bittium mamillanum, Watson (PI. XL. fig. 6). 



Cerithium (Bittium) mamillanum, Watson, Prelim. Report, pt. 5, Joum. Linn. Soc. Lond., vol. xv. 



p. 109, sp. 9. 



Station 120. September 9, 1873. Lat. 8° 37' S., long. 34° 28' W. Pernambuco. 

 675 fathoms. Red mud. 



Shell. — In general aspect very much like Bittium metula (Loven), but narrower and 

 having a still bluuter and more swollen apex. Sculpture : Longitudinals — on the last 

 whorl there are twenty-one small, narrow, longitudinal ribs, which are curved so as to be 

 posteriorly convex ; they appear faintly on the outer circumference of the base ; the line 

 of these from whorl to whorl runs very straight up the spire. The whorls are also 

 microscopically striate in the lines of growth. Spirals — near the suture a spiral thread 

 encircles the top of the whorls, and rises into minute tubercles where it crosses the ribs ; 

 near the foot of the whorls is a strong carination, and here each longitudinal rib projects 

 strongly into a rounded, narrow, longitudinal tubercle ; the base is encircled by a small 

 sharp thread, which is undulated but not tubercled by the longitudinal ribs. Colour 

 translucent white, more ivory than porcellanous. Spire high, narrow, and conical. Apex 

 blunt, inflated, and projecting beyond the contourdines of the spire, as if the two 

 embryonic whorls had been squeezed down and spread out in the operation. They are 

 glossy and quite smooth, but with a trace of spiral arrangement in the microscopic 

 texture. Faint traces of the longitudinal ribs appear toward the end of the second whorl, 

 and the spiral threads appear pretty strongly on the third. Whorls 12, of very gradual 

 increase, slightly concave on the sides, and below the carina sharply contracted in toward 

 the suture. Suture well marked by the contraction of the whorl above it and the slight 

 angular prominence of the whorl below it. Mouth square and small. Pillar very short, 

 perpendicular, broad, with a small, blunt, oblique but not reverted point. Inner lip a 

 very thin layer of glaze. H. 0"22 in. B. 0-06. Penultimate whorl, height 0'025. Mouth, 

 height 0*03, breadth 0-025. 



The sculpture in this species resembles a good deal that of Bittium amblyterum, Watson, and of 

 Bittium metula (Lovun) ; but the details of the sculpture are quite different, and the peculiar form 

 of the apex distinguishes it easily from both. In many respects it greatly resembles Cerithiopsis (or 

 Cerithiclla) Whitcavsii, Verrill, but is in form more cylindrical (or less conical), the apical whorls 



