S ME. 0. A. SATCE ON A REMARKABLE 



in the Amphipoda. It may, however, be merely a specific character without 

 morphological interest. These parts are best seen from the ventral aspect, with the 

 appendages in their natural position, as shown in fig. 4 ; when dissected out the 

 rather peculiar joining of the second joint to the first makes the parts difficult to 

 understand. There is no vestige of the gnatho-basic lobes which are found in 

 Anaspides. 



The second joint is short, of subquadrate form, and from the frontal or upper 

 margin of the outer face there is a linguil'orm lobe (the exopodite), which extends 

 forward to a little beyond the end of the third joint and is transversely divided near its 

 proximal end. 



The third joint is subquadrate and clothed rather densely on the inner face with long 

 setae, most of which are faintly feathered. The fourth is about one-third longer than 

 the preceding one, swollen to a slightly ovate form and bearing a few long setae ; the 

 fifth is quite short and its articulation with the preceding joint permits great flexion ; 

 the sixtli is slightly longer hut not narrower than the fifth ; the seventh is minute, 

 appearing as a broad rounded tubercle, bearing on the apex a row of four stout curved 

 claws. 



Compared with Anaspides there is one joint less in number, due to the complete 

 coalescence of two joints, which I think most likely to be the second and third ; the 

 relative lengths of the third, fourth and fifth are very different, but the three terminal 

 ones are in agreement. As previously mentioned, the appendage does not possess any 

 gnatho-basic lobes. 



Appendages of the Perceon or Mesosome. — All the legs have the corresponding joints 

 almost identical with each other, and, except for being more slender, also with those 

 of the maxillipeds. The first three pairs are of about equal length, the fourth 

 distinctly longer, the fifth and sixth subequal to the anterior three, and the seventh 

 rather longer but not so long as the fourth. The first six pairs have the joints articu- 

 lated, so that the claws point backwards, but the last pair are quite reversed, so that 

 they point forwards ; this is brought about by the reversal of the flexion of the three 

 last joints. There appears to be no information concerning the arrangement of the legs 

 in Anaspides, and I am not aware of any crustacean being quite like Koonimga in this 

 respect, except some Decapods, e. g. Astacopsis serratus, and also Astacus fluviatilis 

 according to the drawing in Howes's biological atlas. However, this chai'acter is not a 

 reliable one for a natural classification, iu proof of which it may be pointed out that 

 must of the Amphipoda and some Isopoda of widely different genera agree in having the 

 anterior lour legs bending backwards, and the remaining three forming another series 

 bending in the reverse direction. This reversal, however, takes place at the articu- 

 lation with the body, but that does not affect the question as to the reliability for a 

 means of classification. Each pair will now be considered in detail. 



The first appendage of the perceon (corresponding to the second thoracic of Anaspides) 

 ( figs. 3, 4, & 15) is of similar form to the maxillipeds, but more slender ; the first joint, 

 together with the branchial lobes, is quite similar, except that the lobes are larger, 



