372 A HISTORY OF KECENT CRUSTACEA 



occurs in the North Atlantic, Astacilla marionis, Beddard r 

 in the Southern Ocean. The young of this genus some- 

 times, if not always, have the fourth segment of the pergeon 

 not elongate, just as in Arcturus. 



Family 2. Idoteidoe. 



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 antennae are not as a rule greatly 

 elongate ; the flagellum may be rudimentary, single- 

 jointed, or more usually multiarticulate. The limbs of the 

 per.geon are usually nearly alike, but the first three pairs 

 are sometimes subchelate, and the last two may be ' mul- 

 tiarticulate.' 



Glyptonotus, Eights, 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 pereeon 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 'dorsatty 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. 



Chcetilia, Dana, 1852. Mr. Miers, in his elaborate ' Re- 

 vision of the Idoteidge,' says: ' The multiarticulate character 

 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 postabdoinen [pleon], and 

 elongated antennules, the relationship of Chcetilia to Glyp- 



