2^ T.\(ii; SK(KiSBER(; 



lias fewiT joiuta than tlie endopodite. With regard to the iiunibur of joints in the eudopodite 

 of the second antenna in tlifferent Ostracod groups I need only refer to what is written about 

 this limb in the second chapter of this work. The weight of the evidence afforded by the position 

 of the end joint of the inner branch is well ilhistrated by the fact that in the H a 1 o c y p r i d s 

 as well as in the P o 1 y e o p i d s the end joint has a dorsal position, when the branch 

 is pointing forwards contrary to the statement of G. W. MOller (see my fig. 12 of 

 Haloci/pru bredrostris). A close comparison between Halocyprids, Polycopids, 

 C V p r i d s, 1) a r w i ii u 1 i tl s, N e s i d e i d s and C y t h e r i d s will also afford good 

 material as to the strength of tlie evidence of the number of the end bristles; it must be 

 described as nil. There is no additional resemblance between the homologized branches, at least 

 according to G. W. MtlLLER — and my own experience does not contradict this idea. The 

 muscular system, for instance, shows, as anyone can easily ascertain, far-reaching differences 

 in this limb in the different Ostracod groups. G. W. MOller stated that he was surprised 

 ,,durch den Mangel jedweder deutlichen morphologischen Beziehung zwischen den einzelnen 

 Gliedern; mindestens fehlte jeder Anhalt dafiir, wie eine Form aus der anderen, oder beide aus 

 einer gemeinsamen Stammform abzuleiten seien" when using the old homologization. He 

 might have experienced the same surprise on comparing the exopodite in, for instance, the 

 C y p r i d i n i d s and the Cytherellids. These are both essentially different from 

 each other — but nevertheless it is certain that they must be homologous. 



The fact that it is not possible to observe any far-reaching morphological agreement 

 between the homologized branches of the Cypridinids, Halocyprids and Poly- 

 copids on the one hand and the other Ostracod groups on the other does not, however, 

 render the homologization carried out by G. W. MCller in any way less probable, as the 

 morphological differences between the former groups and the latter are so far-reaching in other 

 respects as well that no close agreement between these limbs can be expected a priori. 

 Matidibk. Mandible; — This limb appears as a very uniform type in the different Ostracod 



groups. It has not been a subject for any important differences of opinion among preceding 

 authors; we may note, however, that several of these authors have not given any opinion as 

 to the morphological value of its different parts; thus the small appendage on the Cypridinid 

 mandible, which is interpreted as the exopodite in this work, is often called simply ,, appendage". 

 Apart from one important exception I have followed in this work the homologization 

 used by G. W. MtlLLER in his work of 1894. 



According to this writer the mandible, like the second antenna, is almost always deve- 

 loped as a biramous limb. The protopodite is powerful, and in most cases it is distinctly divided 

 into two well developed joints, the coxale and the basale; in some Polycopids even three 

 distinct protopodite joints are to be distinguished on this limb, see my fig. 5 of Polycope setigera; 

 sometimes the protopodite is fitted with two powerful endites, one on the coxale and one on the basale 

 (Halocyprids); in most cases, however, it has only one endite, which is situated on the coxale. 

 The latter endite in, for instance, the Polycopids and C y p r i d s and most of the 

 Cytherids is very powerful, but in the Cypridinids, on the other hand, it is weak 

 and in most cases small and is not used as a masticatory organ; in a number of forms belonging 



