606 THE VOYAGE OF H.M.S. CHALLENGER. 



base, an unvarixed lip, and a round mouth. Sculpture : none, but very feeble lines of 

 growth. Colour glossy white. Spire convexly conical, resembling a somewhat narrow 

 beehive. 1 Apex very bluntly rounded, but the largish round tip rises into view, WJiorls 

 6, of very regular increase, barely convex ; the last is very obsoletely angulated at the 

 edge of the base. Suture very slight indeed, scarcely oblique. Mouth small, sub- 

 quadrately round, not narrowed above. Outer lip thin, slightly contracted above, direct 

 below and hardly curved, subangulated at the corner of the base, patulous on the base. 

 Inner lip rather thin, but well defined on the body, deeply concave at the top of the 

 pillar, on which it is thin and expanded, almost concealing the umbilicus and furrow 

 behind it. H. 0-052 in. B. 0-032. Mouth, height 0*018, breadth 0*017. 



This species somewhat resembles Bissoa concinnata, Jeffr., but has more whorls, and these are not 

 convex, which they are in that species much beyond what the figure (Ann. and Mag. Nat. Hist., June 

 1883, ser. 5, vol. xi. p. 396, pi. xvi. fig. 2) would convey. In that species, too, there are very fine 

 microscopic close-set superficial spirals, not mentioned in the description, but present in the shell, and 

 entirely absent in Rissoa alvearium. In Bissoa obtiisa, Oantraine, which somewhat resembles both 

 the above, the whorls are conical, flat on the sides, and have a deep sharply contracted suture. In 

 JRissoa alvearium they are also conical and flat, but the suture is not^ at all contracted. In Rissoa 

 concinnata they are well rounded, and the deep suture is the result of the meeting curves. 



F. Whorls rounded and smooth (Setia). 



35. Rissoa (Setia) albugo, Watson. 



Rissoa albugo, Watson, Madeiran Rissoae, Proc. Zool. Soc. Lond., 1873, p. 379, pi. xxxv. fig. 17. 

 „ ,, Eeeve, Conch. Icon., vol. xx. pL xii. fig. 114. 



„ jf„ Weinkauff, Conch. Cab. (ed. Kiister), p. 150, sp. 51, pi. xviii. fig. 9. 



February 10, 1873. Tenerife, Canaries. 70 fathoms. 

 Habitat. — Madeira (Watson). 



I recognised this as a Canarian species some years ago, having found it among Rissoas from the 

 Canaries, sent me by Mr McAndrew as dredged by himself. 



36. Rissoa (Setia) callosa, Manzoni. 



Rissoa callosa, Manzoni, Journ. de conch., 1868, vol. xvi. pp. 166, 241, pi. x. fig. 3. 

 ,, „ "Weinkauff, Conch. Cab. (ed. Kiister), p. 153, sp. 56, pi. xviii. figs. 14, 15. 



February 10, 1873. Tenerife, Canaries. 70 fathoms. 



Habitat. — Canaries. 



1 Hence the name. 



