Sea Shells 
sf New Zealand 
Plate VIII 
No. 22 
Plate VIII 
No. 23 
Plate VI 
No. 22 
about a third of an inch in length. Common in the North 
Island. Bay of Islands; Mount Maunganui. 
CERITHIDEA SUBCARINATA (ceration, a small 
horn; sub, under, or less than; carinata, keeled).—A small 
dark-brown or black spiral univalve of about half an inch 
in length, sculptured with longitudinal rounded ribs, and 
without any other decoration excepting a small groove 
running across the uper third of the ribs of each whorl, 
It is found in small rocky pools just below high-water 
mark. 
Throughout New Zealand. Mount Maunganui; Chat- 
ham Islands. 
CERITHIDEA TRICARINATA  (ceration, a small 
horn; tricarinata, having three keels).—A somewhat simi- 
lar shell to the last. It is a small, dark-brown, almost 
black, sharply-pointed, elongated spiral univalve, possess- 
ing about nine or ten whorls, sculptured with longitudinal 
ribs, of which there are about thirteen on the body whorl, 
and spiral grooves, about four on each whorl, which cut 
the ribs up into squarish granules or beads, giving the shell 
quite a decorative effect. On the base are three well- 
marked smooth ribs, or keels, spirally disposed. It attains 
a height of half an inch, and is to be found nestling amongst 
the small seaweed on rocks a foot or so above low-water 
mark. 
Whangarei; Tiri Tiri; Hauraki Gulf; Mount Maunga- 
nui; Lyttelton; Chatham Island. 
SEILA CHATHAMENSIS (seila, a torch; C hathamensis, 
from the Chathams).—A small pointed, elongated, spiral 
univalve, resembling the Screw shell in general appearance 
with its straight outlines, but only three-eighths of an inch 
in height, and one-eighth in diameter at the base. It is of 
a dark brown or bronze colour, and sculptured with fine 
and very distinct, smooth ribs, separated by deep grooves. 
There are five or six ribs on the body whorl, and four on 
the whorl above, the number gradually diminishing towards 
the summit of the spire, which terminates in a protoconch 
of one smooth rounded whorl. The suture is somewhat 
inconspicuous, being merely indicated by a slightly wider 
space between the ribs. The aperture is described as sub- 
quadrangular—that is to say, although the mouth is round, 
there is a suggestion of a four-sided figure about it. There 
Is scarcely any canal to speak of, but a small and decided 
notch at the lower end of the basal lip. An uncommon 
species, it is found on the under sides of boulders at ex- 
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