KEPORT ON THE GASTEEOPODA. 449 



20. Natica (Lunatia) prasina, Watson (PI. XXVII. fig. 9). 



Natica prasina, Watson, Prelim. Keport, pt. 7, Journ. Linn. Soc. Lond., vol. xv. p. 263. 



Station 149c. January 19, 1874. Lat. 49° 32' S., long. 70° E. Balfour Bay, Royal 

 Sound, Kerguelen. 60 fathoms. Volcanic mud. 



Station 149d. January 20, 1874. Lat. 49° 28' S., long. 70° 13' E. Royal Sound, 

 Kerguelen. 28 fathoms. Volcanic mud. 



Shell. — Conically globose, rather high in the spire, with umbilicus closed, thin, with a 

 pale green roughish epidermis. Sculpture : Longitudinals — there are on the lines of growth 

 slight puckerings of the fibrous epidermis. Spirals — there are some slight, open, irregular 

 and unequal furrowings of the surface, with microscopic scratchings. Colour : a pale buff 

 colour below the dull greenish epidermis, which is fibrous, thin, easily rubbed through, 

 but persistent. Spire more or less high, the whorls rising very considerably above each 

 other in high rounded steps. Apex extremely large for the size of the shell, but not 

 prominent, being rounded, with the extreme tip sunk in and generally eroded. Whorls 

 5, of which about 1^ are embryonic ; they are globose, and increase regularly and slowly. 

 Suture deep, very slightly channelled, straight, but towards the end a little oblique. 

 Mouth large, open, circularly oval, little oblique, right-angled above, fully rounded below, 

 with a scarcely perceptible angulation towards the point of the pillar, slightly flattened on 

 the iuner lip ; its height is nearly seven-ninths, of the whole height. Outer Up — leaving 

 the body-whorl at a right angle, it sweeps round very fully and regularly to the pillar ; 

 it is thin. Inner lip a little hollowed, with, on the body, a very slight projection ; there 

 is scarcely any pad at the upper corner of the mouth, and the callus is very thin on the 

 body ; above and at the umbilicus it is thinly and somewhat broadly reverted, so as quite 

 to conceal the opening, or to leave at most a mere chink ; at the pillar it narrows, and 

 there is at this point a slight transverse angulation ; the pillar is the only part of the lip 

 which is at all thickened, and that but sbghtly ; the edge is reverted, rounded, and slightly 

 bevelled back. Operculum is membranaceous, thin, with a distinct and slightly impressed 

 suture, and scored with sharp radiating lines. H. 0'64 in. B. 0'53. Penultimate whorl, 

 height 0-15. Mouth, height 0'49, breadth 0'47. 



Natica globosa, King, from the Straits of Magellan, is somewhat like this, but has a much more 

 depressed spire and longer mouth. Prof. v. Martens was good enough to compare this species for 

 me with his Natica grisea, and from that he says " it differs (1) by being considerably larger, (2) 

 thinner, (3) penultimate whorl less prominent, (4) the last whorl, when seen from the dorsal side, is 

 higher or longer relatively to the breadth, (5) the umbilicus is narrower. I think, therefore, that it 

 is a distinct species, and I see also no other in the Berlin collection which might be identical." 



(ZOOL. OHALL. EXP. — PART ZIAI. — 1885.) Tt 57 



