242 
Miscellaneous. 
dimensions (it measures about 023 metre in length, by 0-10 
metre in breadth), but also for the peculiar arrangement of its 
respiratory apparatus, which is very different from that of all other 
known crustaceans. 
It would appear that the respiratory apparatus of an ordinary 
Isopod would have been insufficient to supply the physiological 
needs of the Bathynomus, and that the addition of special organs of 
greater functional power was necessary. The abdominal false feet, 
which usually in this group constitute alone the branchial apparatus, 
only form in Bathynomus a sort of opercular system, beneath which 
occur the true respiratory organs or branchiae. The latter, con¬ 
sidered individually, resemble little trees or tufts originating from 
stems, which divide again and again, and thus form a regular 
hairy tussock. When examined under the lens they are seen to 
form a certain number of distinct and more or less developed 
bundles; each of these bundles originates in a tubular peduncle 
with membranous and flexible walls, which soon furnishes other 
trunks; and these speedily divide into a quantity of elongated ap¬ 
pendages, nearly similar, but arranged with no regularity, and 
having the appearance of a spindle with delicate walls. 
If a coloured liquid be injected into the sinus situated at the 
base of the branchial feet, the whole of this system may be easily 
filled, and the progress of the liquid may be followed, not only into 
the branchial tree, but also into an irregular network hollowed out 
in the interior of each of the leaflets of the abdominal false feet, 
and comparable to the entire branchial apparatus of the ordinary 
Isopods. A marginal vessel seems to collect the blood which has 
respired, and pours it into the branchio-cardiac trunk. 
In all Isopods, on the contrary, the abdominal false feet are very 
simple ; and when they are complicated in order to fulfil the require¬ 
ments of a more active respiration, this is effected by the folding 
(which is always rudimentary) of the posterior lamina of these 
limbs. 
We know, however, two genera of Isopods in which ramose ap¬ 
pendages appear on the sides of the body, namely the genera lone 
and Kepon in the family Bopyridoe; but between this rudimentary 
apparatus and that of Bathynomus there are fundamental differ¬ 
ences, not only in the position of the branchial tufts, but also in 
their structure &c. 
In its general construction, the grouping of its segments, the com¬ 
position of the parts of its mouth, and the arrangement of its legs, 
Bathynomus undoubtedly belongs to the division of the Isopodes 
marcheurs. It differs from the Sphseromidoe by its free abdominal 
segments and the development of its caudal fin. These peculiarities 
approximate it to the Cymothoadae, and among these to the Cymo- 
thoadiens errants ; but in the structure of the head, antennae, and 
eyes it presents certain characters which separate it from all known 
groups. The eyes are greatly developed, in opposition to what 
might be expected in an animal living at so great a depth and in a 
very obscure medium; each of them is formed of about four thou¬ 
sand square facets; and instead of being placed upon the upper 
