ANISOPODA. 737 



2. Anthura* — In Anthura there is the same Amphipod arrange- 

 ment in the thoracic legs, the series being 4 (or 2+2) : 3, and not 3 : 4, 

 as in Isopods. The genus is, therefore, near Arcturus. 



3. Tanais, Apseudes, Ehoea.f — The thoracic members in Tanais are 

 as in Arcturus, and the three posterior pairs are used in the same 

 manner. The four anterior pairs, Amphipod-like, are in two sets of 

 2+2 (or 1+1+2). Apseudes and Rhoea are closely related to Tanais, 

 and more like Amphipods than Isopods in habit. 



4. Praniza and Anceus.% — The three posterior pairs of thoracic legs 

 belong to a distinct set from the preceding, as in Amphipods. The 

 abdomen is considerably elongated in Praniza and flexible, though still 

 Isopodan in having but a single pair of stylets. 



5. Serolis.\ — The structure of these species and their relation to 

 the Amphipoda and Isopoda are mentioned on a preceding page. We 

 only add here, that the two anterior pairs of thoracic legs differ from 

 the following, indicating the Amphipod series, 2+2:3. 



6. Ancinu8. — On page 749 we have suggested that this genus may 

 possibly be Anisopodan. 



7. BopyridcB.\\ — It is sometimes difficult to distinguish any diffe- 

 rence among the several pairs of thoracic legs of the Bopyri, especially 

 in females. Yet, in males, the Amphipod arrangement is often appa- 

 rent, and besides, there is at times an elongated abdomen, with lateral 

 appendages very unlike those of the true Isopoda. Certain figures by 

 Kroyer illustrate these points. Fig. 1 A, PL 28, of the Voyage to 

 Scandinavia, represents a Bopyrid, called Bajus Mysidis. Five pairs 

 of abdominal appendages are long, and the abdomen has the elongate 

 form and free articulation of Tanais ; at the extremity there is a short 

 caudal pair of stylets. In the male Bopyrus abdominalis, and the 

 young female (figs, lo, lq, PI. 29), the abdomen is similarly jointed, 

 but the appendages appear to be short. In a female, not adult (fig. 

 1?), the thoracic legs are obsolete on one side, excepting the three 

 posterior pairs, — a fact that seems to show that these legs conform to 

 the Amphipod series (4:3). 



* Idotdides Ordinaires, in part, of Edwards, Crust., iii. 124. 



f Asellotes Heteropodes of Edwards, Crust., iii. 137. Apseudes was referred to the 

 Amphipoda by Latreille. 



% Family Pranisiens of the Isopodes Nageurs of Edwards, Crust., iii., 191 ; Amphi- 

 poda according to Latreille. 



§ Cymoihoadiens Eavisseurs of Edwards, Crust., iii. 228. 



|| Isopodes Se'dentaires of Edwards, Crust., iii. 277 ) Epicarides of Latreille. 



