AUSTRALIAN MALACOSTEACA. 169 



on the outer border of the fourth joint. Abdomen punctate and 

 surmounted with a median obtuse crest. Length about 5 in. 



Sydney, etc. 



317. Ibacus antarcticus. A.M. 



Ibacus antarcticus, Humph. Mus. ; Milne-Edwards, Hist. Nat. 

 Crust., t. ii., p. 287 ; Dana, U.S. Explor. Exped., Crust, i., p. 517. 



Orbits situated nearer the angle of the carapace than the 

 middle line. Carapace convex, scarcely narrowing behind, 

 covered with coarse squamiform tubercles, each of which is 

 bordered with a fringe of hairs. Two teeth in front of the large 

 lateral incision of the carapace. External antenna? much longer 

 than broad, their first joint very large and much more prominent 

 than the rostrum, the second armed with ten strong pointed 

 teeth, seven of which are situated on the external border, two 

 between the anterior angle and the articulation of the third 

 joint, and one on the internal border ; lastly the fourth joint is 

 armed on the border with seven strong, triangular, very prominent 

 teeth. No spines on the external border of the external maxilli- 

 pedes. Abdomen tuberculate and hairy like the carapace. 



Australia. "Widely distributed through Eastern Seas. 



Grenus Arctus, Dana. 



liostrum very short, truncate. External antenna? remote from 

 one another. Palp of the external maxillipedes without a 

 flagellum. Branchiae 19. \_D.] 



318. Arctus ursus. 



Cancer ursus minor, Herbst, t. ii., p. 83, pi. xxx. 



Cancer arctus, Roemer, Gen. Insect., pi. xxxii., fig. 3. 



Scyllarus arctus, Eabr., Supp., p. 399 ; Latr., Encycl, pi. 287, 

 fig. 5 ; Lam., Hist, des Ani. s. Vert., t. v., p. 212 ; Desmarest, 

 Consid., p. 182 ; Risso, Crust, de Nice, p. Gl ; Milne-Edwards, 

 Eegne Animal de Cuvier, 3e ed., Crust., pi. 45, fig. 1 ; Hist. 

 Nat. des Crust., t. ii., p. 282 ; De Haan, Fauna Japonica, Crust., 

 p. 151, pi. xxxviii., fig. 2. 



Arctus ursus, Dana, U.S. Explor. Exped., Crust., i., p 51b\ 



