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



tudinals — the whorls are crossed by an immense number of minute, sharp, very oblique 

 riblets, whose course is from right to left ; they extend to the whole base ; at irregular 

 intervals one of these swells to a varix. Spirals — there are similar, but smaller, more 

 numerous, and closer-set spirals, over which the longitudinal ribs rise. Colour porcel- 

 lanous white. Spire high, narrow, conical. Apex consists of 4^ hardly rounded, glossy, 

 conical whorls, parted by a scarcely impressed suture, and rising to a very minute rounded 

 tip. Whorls 10 in all, convex, of regular increase ; the last is small, with a well-rounded 

 base. Suture rather deeply impressed, oblique. Mouth encircled with a strong varix, a 

 little oblong, slightly oblique in both its planes. Outer lip well arched, rounded, con- 

 tracted above, patulous in front. Inner lip narrow, thick, continuous with the outer lip 

 H. 0-1G in. B. 0'05. Penultimate whorl, height 0'02. Mouth, height 0-04, breadth 0*03. 



This is a peculiarly narrow species, of a rather remarkable style of sculpture. 



10. Scalaria (Acirsa) subdecussata, Cantraine. 



Scalaria subdecussata, Cantraine, Bull. Acad. Brux., 1835, vol. ii. p. 388. 



,, „ Cantraine, Mem. Acad. Brux., 1840, vol. xiii. pi. vi. fig. 24. 



Turritella Philippi, Aradas and Maggiore, Cat. Conch. Sicil., 1840. 

 Mesalia striata, Hidalgo, Cat. moll. test. mar. Espagne, &c, Journ. de conch., 1867, vol. xv. p. 394, sp. 2. 



,, „ Weinkauff, Conch. Mittelmeeres, vol. ii. p. 323. 



Scalaria subdecussata, Nyst, Tableau du genre Scalaria, p. 60, No. 295. 

 Acirsa „ Monterosato, Enumerazione, p. 30. 



Mesalia ,, Aradas and Benoit, Conch. Mar. Sicil., p. 187, No. 498. 



Acirsa „ Monterosato, Notes sur coquilles de Palerme, Journ. de conch., 1878, voL xxvi. 



p. 151, No. 91. 

 Scalaria „ Jeffreys, Moll. "Lightning" and "Porcupine," Proc. Zool. Soc. Loud., 1884, 



p. 132, sp. 1. 



February 10, 1873. Gomera, Canaries. 75 fathoms. 



Habitat. — Sardinia, " common " (Cantraine), Mediterranean (Monterosato), Madeira 

 (my own dredging), Canaries (M'Andrew), Atlantic coasts of France and Spain, from 

 20 to 57 fathoms (Jeffreys). 



Fossil. — Pliocene of Altavilla (Tiberi teste Jeffreys). 



This is the Mesalia striata of M' Andrew's Brit. Assoc. Reports, p. 40, but not of Adams (Proc. 

 Zool. Soc. Lond., 1851, p. 279), which is from the Philippines (see Proc. Zool. Soc. Lond., 1855, 

 p. 123). The form of the animal in this species, the operculum, and the arrangement, number, 

 and shape of the teeth in the radula, are exactly those of a Scalaria, of which genus it has also 

 the beautiful purple secretion. If I have classed the species here as an Acirsa, which it certainly 

 is not, the reason is that there is no other subgenus in which it can be put, and that if subgenera 

 are to be admitted at all, it is impossible to call such a shell as this a Scalaria pure and simple. It 

 is the least typical of all Scalarias. 



