372 A HISTORY OF RECENT CRUSTACEA 
occurs in the North Atlantic, Astacilla marionis, Beddard, 
in the Southern Ocean. The young of this genus some- 
times, if not always, have the fourth segment of the pereeon 
not elongate, just as in Arcturus. 
Family 2.—Idoteide. 
The body is ovate or oblong, or more or less oblong- 
ovate. The mouth-organs and pleon and its appendages 
are nearly as in the preceding family, but the maxillipeds 
sometimes have the ‘ palp’ become three-jointed by coa- 
lescence. The second antenne are not as a rule greatly 
elongate; the flagellum may be rudimentary, single- 
jointed, or more usually multiarticulate. The limbs of the 
pereeon are usually nearly alike, but the first three pairs 
are sometimes subchelate, and the last two may be ‘ mul- 
tiarticulate.’ 
Glyptondtus, Hights, 1852, has the maxilliped-‘ palp’ 
three-jointed, the two terminal joints being fused and also 
the two that precede them. The first three pairs of limbs of 
the perzeon have the sixth joint dilated and are subchelate. 
The pleon has three or four complete sutures; the stilets 
on the second pair of pleopods in the male are very 
elongate ; the outer branch of the uropods is minute. 
Glyptonotus antarcticus, Eights, being ‘dorsally sculptured, 
corresponds with the generic name. It attains a length of 
three inches and a half by a breadth of an inch and three- 
quarters, and is, therefore, one of the monster Isopods. 
The Arctic species, which also occurs in the Baltic and the 
depths of the Swedish Lakes, Glyptonotus entomon (Linn.), 
is not much smaller than the preceding. Chiridotea, 
Harger, 1878, is regarded by Miers as a synonym of 
Glyptonotus. 
Cheetilia, Dana, 1852. Mr. Miers, in his elaborate ‘ Re- 
vision of the Idoteide,’ says:—‘ The multiarticulatecharacter 
of the sixth and seventh thoracic legs is probably not a 
character of the importance assigned to it by Dana. In 
its ovate form, four-segmented postabdomen [pleon], and 
elongated antennules, the relationship of Chetilia to Glyp- 
