Fam. Si gi i nzidai . 

 Seguenzia Jeffreys. 



,. S UU n. sp. PI. XII, fig. 4; PL XV, fig. 12. 



119 8'.s 1".. [301 M. Fine grey mud. 1 Spec. 



Shell ui"' ■ for the genus, conical, scalar, urabilicate, whitish. Whorls about 7. 



, upper whorls eroded, lower ones each with thr.ee spiral lirae, of which the upper 



il .1 little distance from the shallow hut distinct suture, which is slightly undulate; 



from tl.' liration to the second, the shell is slightly convex, this latter liration is strong, 



ninent and divides the whorls in two subequal parts; below this liration the shell is concave 



rds the basal or peripheral liration, which in the upper whorls, runs just in the suture and 



in the last one borders the basal surface; these lirations are slightly spinous ; distinct undulating 



plications run from one to the other of the lower lirae, with the convex side towards the 



aperture, on the upper part they are directed in an opposite way, being less distinct about 



halfway the interspace between the upper and median liration; moreover the whole shell is 



covered with much weaker striae, having the character of growth-striae and traces of more 



remote spiral striae. Basal face subconvex, hut quite flat in the centre, with a shallow groove 



between the peripheral keel and the first of the basal lirae, this space is rather smooth, though 



crossed by plicae running from the peripheral spines in an oblique direction; the outermost of 



the basal lirae, which is not broad, is foliowed by two similar ones, about as strong as their 



interstices, the central ones, fïve in number, increasing in breadth towards the centre, (one of 



them nearly doublé) being larger than the interstices, these lirae are connected by small radiating 



riblets in the interstices; umbilicus horderee! by a liration, consisting of a row of subquadrate 



beads, this umbilicus is pervious, funnclshaped, its wall is radiately striated and has one faint 



spiral rib. Aperture rounded-subquadrate, its right margin incomplete, its columellar margin 



curved, with a denticle in the basal part, it is slightly reflected over the umbilicus. Interior 



nacreous, (the nacreous texture of the inner layers is clcarly visible on some of the exterior 



parts, where the outer layer has been removed by accidents during the youth of the animal). 



Alt. 4'/,., lat. 5'/, ; ; apert. alt. r/ r lat. 2 a / 4 ; diameter of umbilicus about 1 MUI. 



This species has by its conical shape some resemblance with S. trispinosa Watson, but 



that species is considerably smaller, with less distinct spines, which have more the character of 



rounded tubcrcles, it has smooth interstices, without the conspicuous plications of the new 



species. The circumstance that the base of the specimens of trispinosa which 1 could compare is 



much smoother, seems to give no reliable distinguishing-character, at least Watson ("Challenger"- 



p. 1 ioj says : "has some faint spirals". I have named the new species in honour of 



Mr. J. (.'. Mi.i.vii.i., who has kindly sent me for comparison all his materials of this genus. 



to the radula of this species, it is a very small and rather obscure object, and only 



pieces, I could get an idea of the shape of the teeth, the uncini quite covering 



lian rows, and crossing even the uncini of the opposite side. The rhachidian or median 



subquadrate basal part, with rounded, convex posterior and less convex lateral 



70 



