REPORT ON THE GASTEROPODA. 445 



below which the narrow umbilical furrow cuts deeply into the thickness of the pillar, 

 whose edge is bevelled off from without and from within ; towards its point the pillar is 

 thickened by the feeble circumumbilical carina, which is rather suddenly developed and 

 made distinct at this point. Umbilicus consists only of the channel or gutter, which 

 twists round the pillar callus and disappears behind it. H. 0327 in. B. 036. Penulti- 

 mate whorl, height 0"075. Mouth, height 0-29, breadth 0T6. 



Brazier, in the " Chevert " Exped. Marine Shells (Proc. Linn. Soc. New South Wales, 1877, vol. i. 

 p. 237) gives what is, I suppose, this species under the name of Lunatia variabilis, Recluz, and ascribes 

 as its habitat North and North-East Australia and New Caledonia, 5 to 30 fathoms. In the British 

 Museum there is a Natica presented by McAndrew, and in his handwriting and initialed by him it is 

 attested to come from Suez ; probably it was his own dredging there (see his Report on Suez Dredgings, 

 Ann. and Mag. Nat. Hist., 1870, vol. vi. p. 437). It bears the name Natica marmorata, H. Adams. 1 

 With that shell the Challenger species described above is identical. But Natica marmorata, H. Adams 

 (Proc. Zool. Soc. Lond., 1869, p. 274, pi. xix. fig. 8), is certainly a mere synonym for Natica variabilis, 

 Reel. ; and consequently the present species, which has hitherto passed for Adams's Natica marmorata, 

 requires both an individual name and a description, for it is beyond doubt distinct, though at first 

 sight deceptively like, and, indeed, from this very fact the name proposed for it is borrowed. 



Compared with Natica variabilis, Reel., Natica pscustes is a broader and flatter shell, with a more 

 depressed spire ; the apex is blunter, the embryonic whorls are 2? instead of 3, and are larger. Its 

 coloration is very like that of Natica variabilis, especially in the white band with large chestnut spots 

 below the suture ; but it has these spots less confluent, more ruddy, and there is none of the purple 

 tinge on the spire which is traceable in that other. The coloured ornamentation in Natica pscustes is 

 a distinct network of minute, sharply defined, delicate lines, amidst which occur two or three spiral 

 zones of lanceolate white spots where the brown lines are fewer. In Natica variabilis, on the other 

 hand, this coloured ornamentation is rather a mass of confused blotchy stains, with one or two spirals 

 of brown arrow-heads parted by little white dots. There are very many other minute differences ; 

 but perhaps the best distinctive feature of all is that, when looked at perpendicularly to the centre of 

 its axis, with the shell on its mouth and the base toward the observer, the oblique line of the base is 

 in Natica pseustcs quite continuous and unbroken, while in Natica variabilis in all stages of growth 

 this basal line is abruptly interrupted by the projection of the pillar and the sweep of the basal lip. 



As this sheet is passing through my hands for final revision, I have been enabled, through the 

 kindness of Mr Alfred Hands Cooke, M.A., curator in Zool. Mus. Cambridge, to examine McAndrew's 

 own specimens, dredged by himself, and marked " Natica marmorata, H. Ad., Gulf of Suez." Several 

 of these specimens retain their operculum, which is so absolutely identical with the operculum of 

 Natica variabilis, Reel., from Madeira and Tenerife, that my estimate of the distinctness of the two 

 species is very much shaken. 



17. Natica xantha, 2 Watson (PI. XXVII. fig. 8). 



Natica xantha, Watson, Prelim. Report, pt. 7, Journ. Linn. Soc. Lond., vol. xv. p. 262. 

 Station 150. February 2, 1874. Lat. 52° 4' S., long. 71° 22' E. Between Ker- 

 guelen and Heard Island. 150 fathoms. Coarse gravel. Bottom temperature 35 0, 2. 



1 McAndrew in his Report (loc. cit.) gives "H. Adams" as his authority for this identification, but adds 

 that "Miirch questions the species being identical." The identification being erroneous, McAndrew's citation of 

 the Canaries for the Suez species must be suppressed. 2 2ja»^c, yellow. 



