120 
“TERRA NOVA - ’ EXPEDITION. 
the horizontal plane. It is noticeable that they retain the scaly patches on both rami 
which are used, by the hermit-crabs which inhabit hollow objects, to give foothold on 
the inside of their homes. 
With regard to the habits of Porcellanopngums, some information may be gained 
from the statements of the naturalists who collected the specimens at present known to 
science. P. edward-si was originally taken in shallow water (down to 5 m.) at Campbell 
Island and Stewart Island, living among sea-weeds, and was expressly stated by Filhol 
not to live in a shell. Chilton records it dredged at the Snares in 60 fathoms. The 
“ Terra Nova’’ specimen, which I have rather doubtfully referred to the same species, 
was trawled in 70 fathoms off the North of New Zealand, on a bottom of sand and 
rock. P. platei was obtained on the shore at Juan Fernandez, and Plate, who collected 
it, stated that it deckt die Pier mit einer Muschelschale zu. Lenz, for no very obvious 
reason, distrusted Plate’s statement, and held that the animal’s abdomen kann nach 
coni auf den Riieken geklappt werden, and in that position was mistaken by Plate for 
the shell of a bivalve mollusc ! This very improbable supposition may be dismissed, 
in view of the subsequent evidence by which Plate’s statement is confirmed for other 
species. P. trident at us has been obtained in 54-59 fathoms off Wata Mooli in New 
South Wales, and between tidemarks in the Kermadec Islands. Oliver, by whom it 
was collected in the latter locality, found it under stones, and states that it was not 
common, and that it never uses a spiral shell, but manages to keep on its back a single 
valve of a bivalve mollusc’s shell, or a vacant Siphonaria or limpet shell. P. japonicus 
is as yet. only reported from the Uraga Channel in Japan, where a single specimen was 
taken. No information is available as to the depth or nature of the habitat in which it 
was found, but it is stated to have carried over its back a Cardium shell, held in 
position by the telson of the crab fixed in the umbo. 
It appears that Porcellanopagurus has a wide distribution in the extra-tropical 
parts of the Pacific, that each of the several as yet widely separated localities in which 
it has been taken possesses its own representative of the genus, that it ranges from near 
high-water mark to a depth of at least 70 fathoms, and that the same species may 
extend throughout this vertical range. As will be explained later, while the distinctions 
and affinities of the species are as yet obscure, it seems that the New Zealand, Chilian, 
and Japanese forms resemble one another more closely than any of them resembles 
the Australian-Kermadec species. In most respects there is no indication that the 
habits of the genus differ substantially from those of the ordinary hermit-crabs, but the 
mode in which the abdomen is protected is unique among Paguridea. Some kind of 
shallow, non-spiral shell found by the animal is held over the back, covering, to judge 
by the extent of the egg-mass, the abdomen and the soft part of the cephalothorax. 
How the shell is kept in position is not clear. That the telson and uropods should be 
wedged into the umbo suggests itself at once, and this was the case in Balss’ specimen, 
but if, as Oliver states, a limpet shell is sometimes used, the abdominal organs alone 
will not suffice to retain the protecting structure. It- may well be that the hinder two 
