276 A HISTOEY OF EECENT CRUSTACEA 



Muchcetomera^ with two species typica and tennis from 

 the Pacific, agrees with Erythroiis in the form of the very 

 short, lamellar, unincised telson. The scale of the second 

 antenna3 is smooth on the outer margin. The legs are 

 very slender. Some of the joints of the legs, the pleopods 

 in both sexes, and the uropods, are fringed with long settB, 

 from which circumstance it may be supposed that the 

 generic name is derived, meaning ' with the parts beauti- 

 fully hairy.' Professor Chun comments on the astonishing 

 length of the upper antennae in the type species, which 

 he regards as a transitional form between Mijsis and his 

 own Arachnomijsis Leuclmrtii. 



Siriella^ Dana, was originally named Gynthia, by 

 Vaughan Thompson, but the name was preoccupied, and 

 Dana's Siriella takes precedence of White's Gynthilia. The 

 genus is characterised chiefly by the structure of the legs, 

 ' which are more decidedly unguiculate than in any other 

 known genus ofMysidans,' and have the sixth joint entire 

 or subdivided into two articulations only ; also by the pleo- 

 pods of the male, which are natatory, and have the ' basal 

 lobe of inner branch usually transformed into two gill-like, 

 more or less spirally twisted stems.' The outer branch of 

 the uropods is broader than the inner, and has an imperfect 

 articulation at the apex. The telson is elongate, densely 

 spinose at the edges, with the apex not incised. The 

 species are numerous, and many of them are met with at 

 the surface of the sea, far from the coast. The British 

 species, as far as at present known, are : 1. iSiriella norve- 

 fjica, Sars, in which the third joint of the first antennae has 

 three setae on the inner margin, and between the spines 

 at the angles of the telson three spinules, of which the 

 central is the largest. 2. Siriella Glatisii, Sars, of which 

 Norman gives the distinguishing characters as ' the single 

 seta on inner margin of last joint of peduncle of antennules, 

 the slender legs and claws, and three equal-sized spinules 

 between the ultimate spines of the telson.' 3. Siriella 

 jaltensis, Czerniavsky, identified by Norman with the later 

 Siriella crassipes^ Sars, in which the form is somewhat 

 more robust and the legs much stronger than in the 



