ISOPODA. 
17 
The gnathopod (fig. 3b) is a large, tapering six-jointed structure, articulated to 
the body laterally and curved forwards over the mid-ventral line ; it is shielded 
externally by a curved and projecting flange of the exoskeleton. The first joint is 
short and stout, only indicated in the figure ; all the other joints except the terminal 
one are large, flat, and broad; the first of these—the second in point of size—has a 
fringe of small setae externally and six rather short plumose setae distally on the inner 
margin. The next joint is the largest, and its inner margin is fringed with large 
plumose setae; externally there are a few small setae distally. The three following 
joints are scarcely as long as the second, the terminal one being minute. Collectively 
they taper to a blunt point; the third has plumose setae all along the inner margin, 
and small fine setae externally, the other two have these fine setae all around, but the 
penultimate one bears a group of long, simple setae near its distal extremity. 
The proportions of these joints are 4. 6. 3. 2. 0'5. 
The pereiopoda are all very much alike. In the first pair the second and third 
joints together are scarcely as long as the first, the carpus is about as long as the 
preceding, the prcpodus is longer, the dactylus is about half its size. The proportions 
are not quite the same on all the limbs, but in all cases the ischium and merus are 
expanded on their outer margin ; in the merus this expansion becomes a forwardly 
directed lobe. Small groups of setae occur on these swellings, and a few smaller ones 
are scattered elsewhere. One or two small spines may occur on the propod us. 
A single specimen was taken oft* Coulman Island in 100 fathoms, 13th January, 
1902. 
iEGA. 
This well-known genus, established by Leach in 1815, now contains some twenty- 
five species from all parts of the world. The following species was first taken on the 
French Antarctic Expedition. 
iEGA ANTARCTICA. 
(Plate II.*) 
sEga australis Richardson (12), pp. 4-6, not Whitelegge, Mem. Austral. Mus. iv. (1901), p. 229. 
Specific characters :— 
No process on the propodus of the first three pair of pereiopoda. 
The enlarged endopodite of the uropoda. 
This species, of which several specimens were taken, attains a length of 28 mm. 
and a width of 13 mm. 
The cephalosome is small, its anterior margin is slightly rounded, and a stout but 
short rostrum projects between the antennre ; its posterior margin is rounded, but not 
quite evenly, the eyes are very distinct, rather small, lateral in position, and irregular 
in shape. 
* The legend should be as above, and not as it was printed off. 
VOL. v. 
K 
