MOLLUSCA OF THE ' CHALLENGER ' EXPEDITION. 257 



Eeport on Suez dredgings, Ann. & Mag. Nat. Hist. 1870, vi. 

 p. 437). It bears the name JV. marmorata, H. Adams*. "With 

 that shell the * Challenger ' species described above is identical. 

 But JST. marmorata, H. Ad. (P. Z. B. 1869, p. 274, pi. xix. fig. 8) 

 is certainly a mere synonym for N. variabilis, Reel. ; and con- 

 sequently the present species, which has hitherto passed for 

 Adams's AT. 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 pro- 

 posed for it is borrowed. 



Compared with N. variabilis, Reel., N. pseustes 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 AT. 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 A. pseustes 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 JV. 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 perpen- 

 dicularly 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 JV. pseustes quite continuous and unbroken, while in A", varia- 

 bilis in all stages of growth this basal line is abruptly interrupted 

 by the projection of the pillar and the sweep of the basal lip. 



4. Natica stjtukalis, n. sp. 



St. 149 d. Jan. 19, 1874. Lat. 49° 32' S., long. 70° 0' E. 

 Balfour Bay, Royal Sound, Kerguelen's Land. 60 fms. Mud. 



Shell.— Conic-oval, thin, umbilicated, with a coarse, brown 

 epidermis, suture channelled. Sculpture. Longitudinals — the sur- 

 face is covered with fine, close-set, hair-like stria3, indicating lines 



* M 'Andrew in his Eeport (I. c.) gives " H. Adams "as his authority for this 

 identification, but adds that " Morch questions the species being identical." The 

 identification being erroneous, M 'Andrew's citation of the Canaries for the Suez 

 species must be suppressed. 



LIKN. JOURN. — ZOOLOGY, VOL. XV, 20 



