472 FUNAFUTI ATOLL. 
A single specimen was taken in company with the Gorgonide 
described ante p. 308 — 320, by tangles hauled from eighty to 
forty fathoms on the outer and western slope of Funafuti. It 
differs considerably from a specimen (apparently typical) received 
from New Caledonia, being of a chrome-orange colour, with a 
pale peripheral band, 5 mm. long by 2 broad. Whereas the New 
Caledonian example is of a peach-blossom pink colour, 6} mm. 
long, 3 mm. broad, and of a stouter build. Both show the granu- 
lations noted in the original description which Dall points out as 
characteristic of the genus.* ; 
Garrett found this in Samoa and Fiji, and Melvill and Standen 
received it in abundance from Lifu, Loyalties.+ 
THETIDOS, gen. nov. 
A member of the Mangiliine, distinguished by three stout 
tubercles seated on the lip within the aperture, and by a globose, 
tilted, two-whorled protoconch, which is closely spirally grooved 
throughout. 
The new species, which typifies this proposed new genus, stands 
apart from almost all Pleurotomide, with regard to the few 
large denticules which defend the aperture. The thickened lip and 
anal notch throw it into Tryon’s subfamily Mangiliinze, and among 
the members of that, Glyphostoma makes the nearest approach. 
Glyphostoma has smaller and more numerous denticules, and an 
apex which in G. gabbw is thus described by Dall :—“ nucleus 
acute, three-whorled, the first whorl smooth, rounded, tilted, 
minute ; the others smooth, polished, keeled on the periphery.” { 
This description fits others I have examined such as G’. mallets. 
In various instances the protoconch of Mangelia is shown by 
Watson to have delicate, longitudinal ribbing. The genus Clathur- 
ella has a peculiar raised mesh-work over all the whorls of the 
protoconch, as here illustrated in the case of C. irretita, and which 
has been beautifully figured in several instances by Watson in 
the ‘‘ Challenger” Report. The apex which Cossman gives as 
characteristic of Clathurella is, however, quite different.§ 
Opinions on the systematic importance of the Pleurotomoid 
protoconch are conflicting. Watson remarks that :—‘“ sculpture 
and form of apex may probably serve as the safest basis of classi- 
fication in the whole group.”|| On the contrary Dall has expressed 
his opinion that:—‘‘so far as our knowledge goes, nuclear 
* Dall—Bull. Mus. Comp. Zool., xviii., 1889, p. 108. 
+ Melvill & Standen—Loe. cit., p. 402. 
t{ Dall—Loc. cit., p. 109. 
§ Cossman—Essais de Paléoconchologie comparée, 1i., 1896, p. 122. 
|| Watson—Chall. Rep. Zool., xv., 1886, p. 361. 
