74 CERITHIIDA. 
Sub-Family—Potamidine. 
Operculum circular, of many whorls. Shell usually covered with a 
brown epidermis ; the fore-part of the aperture more or less channelled 
not produced into a beak. 
Genus, CERITHIDEA—Swainson. 
Eye pedicels, very long and thick, connate with the tentacles 
nearly to their tips. Shell turreted ; apex of spire more or less decolla- 
ted; aperture rounded, slightly emarginate anteriorly, with a dilated 
thickened margin.* 
C. alternata, Hutton, CALM, p. 26, not Cerithium alteratum, 
Sow. Whorls deeply spirally grooved, with a small ridge in the bottom 
of each groove, and transversely plicated ; outer lip expanded ; yellow- 
ish-brown ; interior white, with spiral bands of purplish-black. 
Length, ‘95; breadth, °38 ; angle of spire, 23°. 
Tauranga. A single specimen only in the Colonial Museum, Wel- 
lington. 
GC. bicarinata, Gray; Dieff. N.Z.ii., p. 241; Voy. Erebus and 
Terror, Moll., pl. 1, f, 20; Reeve, Conch. Ic. ( Cerithidea) f. 27; C. lutu- 
lentum, Kein Mon. Certth, pl. 23, 7-1; Whorls rather convex, obsoletely 
spirally striated, and transversely plicated ; the body whorl with two 
spiral ridges on the anterior end, separated by a concave groove ;_ black- 
ish-purple, generally with a rough brown or reddish-brown coating. 
Length, 1°12; breadth, ‘38; angle of spire, 23°. 
Common in the North Island, not found south of Banks Peninsula. 
C. nigra, Hombronand Jacquinot Voy. Pole Sud., pl. 24, f: 34-36 5 C. 
subcarina, Sowerby ; Reeve, Conch. Lc. ( Cerithidea) f. 28; C. australis, Gray, 
Dieff. N.Z.,ii., p.241 ; nec. Lamark. Whorls nearly flat, shghtly transversely 
plicated ; body whorl with two spiral grooves at the anterior end ; brown- 
ish-black, often with a brown coating ; interior dark purple, with one or 
two lighter bands. 
Length, °45; breadth, 17; angle of spire, 28°. 
Auckland to Dunedin. Chatham Islands. 
Genus, BITTIUM—Leach. 
Operculigerous lobe with rudimentary expansions on each side, and 
furnished with a roundish, lanceolate cirrus (Lovén). Operculum sub- 
circular, of four volutions. Shell turreted, granular, often with irregular 
varices ; aperture with aslight canal in front, not produced nor recurved ; 
inner lip simple ; outer lip acute, not reflexed, nor expanded. 
B. terebelloides, v. Martens, Critical list of the Moll. of N.Z., p. 
26; C. cinctum, Hutton, C.M.M., p. 27. Conical, turreted, yellowish 
on the upper three whorls ; body whorl with four smooth spiral keels of 
* Orithium bicolor and C. striatum of Hombron and Jaquinot, are quite unlike 
any shell found in New Zealand, and are probably Polynesian or Australian species. 
