228 A HISTORY OF RECENT CRUSTACEA 



It has been ascertained by Sars that a curious form which 

 Kroyer described under the name of My to Gaimardii is 

 one of the larval stages of this seven-keeled Sabinea. In 

 1842 Kroyer also instituted the new genus Argis, to re- 

 ceive the Arctic Grangon lar, described by Owen in the 

 ' Zoology of Captain Beechey's Voyage.' Some years later 

 Brandt established for the same species the genus Necto- 

 crangon, meaning ' the swimming shrimp,' in allusion to 

 the swimming properties of the very dilated fourth and 

 fifth pairs of legs. But, however appropriate, the name 

 must yield priority to Argis. 



Sclerocrangon, Sars, 1882, has a hard and thickly in- 

 crusted integument, a rostrum expanded below into a 

 hatchet shape, a very short finger to the second legs, and 

 the pleopods with the inner branch much shorter than the 

 outer. This genus has been established to receive the 

 Cancer Boreas, described in 1774 by the arctic voyager, 

 J. C. Phipps, afterwards Lord Mulgrave. To the same 

 genus is referred another Arctic species, the Crangon sale- 

 brosus of Owen, and with less certainty the Mediterranean 

 Crangon cataphractus, Olivi. 



Pontocdris, Spence Bate, 1888, with two species from 

 the south of New Guinea, has a multicaiinate carapace, 

 short chelate second legs, and a branchial formula nearly 

 the same as that of Pontopliilus. 



Rhynchocinetes, Milne-Edwards, 1837, derives its name 

 from the circumstance that the very large lamellate ros- 

 trum is articulated with the carapace. The species Rhyn- 

 chocinetes typus, Milne-Edwards, is found on the coasts of 

 New Zealand, Australia, and Chili. 



Legion 2. Polycarpinea. 



The name signifies literally ' many-wristed,' and the 

 distinguishing character of the legion is that in the 

 slender second pair of trunk-legs the carpus, wrist, or fifth 

 joint is multiarticulate, that is, subdivided into a greater 

 or less number of minor joints. It includes four families, 

 Nikida3, Alpheidas, Hippolytidas, and Pandalidas. 



