92 TROCHID&. 
stellated ; aperture angled outside ; operculum shelly, concave outside, 
with a spiral rib. 
CG: cookii, Lomark; Leite: 130s sO.GiG:,.. 1.0.5. Wa ipalzeas 
pl. 60, f. 19-23; Cookta sulcata, Adams, Gen. Moll, pl. 45 f- 33 Chenu, 
fi 2581. Conical, body whorl rather ventricose ; whorls rounded, 
obliquely plaited and crossed by oblique rough imbricating laminze 
sloping the opposite way to the plaits ; central part of base smooth, 
hollowed in the middle ; pinkish-brown ; pearly inside. 
Length, 2°25; breadth, 3:5; angle of spire, 86° to 92°. 
Common in the North Island, very rare in the South. Chatham 
Islands. 
GC. davisii, Stowe, Trans. N.Z. Inst., iv., p. 218. Conical ; body 
whorl sharply angled and keeled; whorls slightly rounded, obliquely 
plaited and crossed by oblique rough imbricating laminz sloping the 
opposite way to the plaits; central part of the base smooth, scarcely 
hollowed in the middle; pinkish-brown ; pearly inside. 
Length, 3°65; breadth, 3°3 ; angle of spire, 57° to 60°. 
Cook Strait and Blind Bay. 
The spire is much more acute than the last, but perhaps it is only a 
variety. 
C. imperialis, Zamark, 1c, ix., p. 122; 0.& G, La, iii, Z 
226, pl. 61, f. 1-4; Woodward’s Manual of the Mollusca, pl. 10, f 4; 
Hogg, Trans. Micros. Soc., 1866, pl. 11, f- 46 (teeth.) Conic; obtuse ; 
whorls convex, with spiral scaly ribs, and a spinose radiate margin ; 
spines curved to the left and backwards; perforation funnel-shaped, 
extending to the apex; above purplish or reddish-purple ; base nearly 
white ; interior iridescent. 
Length, 1°8; breadth, 3°5 ; angle of spire, 110°. 
From Hauraki Gulf to Stewart Island. Chatham Islands. 
In the young shell the marginal spines are fewer and longer than in 
older ones. As the animal gets older the upper spines break off to the 
base, and get so covered with coralline growth that they are difficult to 
distinguish. 
Sub-Family—Rotelline 
Rostrum rudimentary ; frontal lobes greatly developed ; operculum 
horny, thin, of many gradually enlarging whorls finely ciliated on the 
outer edge. Shell orbicular, depressed, polished, porcellanous ; umbili- 
cal region often covered with a large callus. 
Genus, ROTELLA—Lamark. 
Orbicular, depressed, imperforate, polished ; base convex and cal- 
lous ; mouth sub-rotund ; inner lip ending in a simple point. 
R. zealandica, Hombron and Jacquinot, Voy. Pole Sud. Moll., p. 
53, pL. 14, f. 5-6; Reeve, Conch. Ic., f- 11; Umbonium szealandicum, 
Adams, P.Z.S., 1853, p. 189; Chenu, f- 2604-6. Body whorl rather 
