angles, gives rise to the specific name, clathrata, from its 
lattice-like arrangement. The upper whorls are turretted, 
rising tower-like in successive tiers or steps, rather square 
at the shoulders, the spire being comparatively small, and 
terminating in a sharp apex, the body whorl large in pro- 
portion to the whole shell, and having a large mouth, with 
a crinkly and sharp outer lip. There is a decided umbili- 
cus. It is found throughout New Zealand between tide 
marks (Iredale) and in deep water. 
Mount Maunganui; Chatham Islands; Bounty Island, 
and The Snares. 
JANTHINA BALTEATA ( janthina, violet-coloured ; 
balteus, a belt) This is one of the beautiful Violet Sea 
snails, commonly called Storm shells. There are three 
species native to these waters, but as they are all pelagic 
in their habits—that is, inhabiting the open sea—they can 
only be procured when washed ashore on an ocean beach. A 
curious feature connected with them is that they construct 
an unsinkable raft of clear, colourless, gelatinous material 
enclosing air bubbles. This raft, which is made by both 
sexes, is utilised by the female to carry her eggs. It can 
be detached when no longer required, but the animals are 
often caught unawares, and the raft is then the means of 
their undoing, for they are driven ashore in great numbers 
when gales are blowing. It has been stated that these ani- 
mals float with the base of the shell upwards, and this is 
given as the reason why the colouration of the shell is so 
much lighter on the spire. In the case of the J. balteata, 
the upper portion of the spire is certainly much paler than 
the base; in fact, it is almost white, and it is well known 
that absence of sunlight will decrease the production of 
pigment in shells, as well as in other forms of animal life. 
That is why our New Zealand mollusca are, as a rule, 
possessed of more sombre-hued shells than are the shellfish 
peculiar to tropical seas. Seeing, however, that there is 
not the same difference in colour in the other Janthinidae, 
the theory is not altogether convincing. One day, during 
a pronounced storm, I picked up about forty J. balteata, 
alive, and each one equipped with a raft; and, on arriving 
home, placed them in a bowl of water. They certainly 
floated, but, contrary to my expectations, they floated with 
the mouth directly upwards, and, consequently, the base and 
the spire were both equally exposed to the sunlight; so 
we may safely assume that there are factors other than 
sunlight concerned in the formation of colour. The speci- 
mens in question were found in company with numbers 
of small jellyfish, a species of Velella, beautiful little crea- 
49 
Plate V 
No. 18-18a. 
Sea Shells 
of New Zealand 
