Sliidios on iiiariiic Ostraroils "il 



homologous with tlio oxopodite, but with an epipodial appendage, an explanation tliat is, 

 by the way, also supported by the function of this organ. 



On this, as on the following, limbs, the endites arc nuniljered proximally distally. 



Maxilla: — The morphological interpretation of the different parts of this limb Maj-uin. 



presents considerably greater difficulty than an explanation of the second antenna and the 

 mandible, a fact that is clearly reflected in the j^receding literature. A detailed study of the 

 different types of maxillae in Polycofidae and a comparison between the state of affairs in 

 this family and in other groups ought, however, to render possible a solution of this problem 

 that, if not absolutely certain, is nevertheless fairly certain. 



The maxilla of Polycofsis serrata G. W. Muller (of. G. \\. MllLLEH, 1894, pi. 7. i-;bi,npidne. 

 fig. 61 — reproduced in fig. Ill: 1 of the present treatise) represents the simplest type within 

 the family Polycopidae; it may be described as a rather straight, typically biraraous limb, 

 presumably of a fairly primitive type. Its protopodite, which is fairly strong, consists of two 

 well developed joints, coxale and basale, proximally of whicli there is a somewhat weaker 

 joint, the procoxale. The exoj^odite and the endopodite, both of which are situated distallv 

 on the basale, the former weakly two-jointed, the latter distinctly threejointed, are also fairly 

 well developed; the former is somewhat weaker than the latter. The protopodite has on the 

 procoxale and tlie coxale slight indications of three endites armed witli bristles; there are 

 some ventral bristles on the basale as well. No epipodial appendage is developed. In other 

 forms of this family, e. g. Poly cope rostrata G. ^^^ MuLLER and P. tuberosa G. W. MCller, 

 the maxilla differs from the preceding type by liaving the basale, the endopodite and the 

 exopodite bent ventraUy and by an increase in the strength of the three endites on the 

 procoxale and the coxale; the basale, on the other hand, has no endites. In both these 

 species the exopodite shows no division into joints; in the former one the endopodite is still 

 distinctly three-jointed, while in the latter this branch too is unjointed; in tliese species too, as 

 in all the others belonging to this family, the maxilla has no epipodial appendage. Cf. G. W. 

 MULLER, 1894, pi. 7, fig. 13 (reproduced in fig. Ill: 2 of this treatise) and fig. 27. 



The maxilla found in the families Vyjrridinidae (in the scope given to this family in the <ui>'-i<liiii<tae ami 

 present work) and Sarsiellidae (i. e. in all the Cypridinids except the families Rutidermatidae 

 and Asterofidae) shows a type that agrees rather strikingly witli the maxilla of Polycopc 

 rostrata and P. tuberosa (see fig. Ill: 3). TIk; morphological explanation of this limb in these 

 families, which is given in the present work on the basis of a comparison with these two species, 

 may accordinglv be considered as fairly well grounded. In these two families the protopoflitc 

 of the maxiUa is strongly developed and is more or less distinctly divided into joints; in 

 most cases two well developed joints, coxale and basale, can be observed, proximally of which 

 a third joint, the procoxale, is sometimes marked off. The procoxale and the coxale arc 

 (at least in all the species I have investigated or in which I was able to ascertain the conditions 

 with the help of the literature — except in the genus Psetuhphilomedes) armed with three 

 endites; these endites are in most cases very strongly developed, considerably more strongly 

 than in the two last-mentioned Poly cop ids; the basale, on the other hand, has no 

 trace of any endites. Tlie basale has two appendages distally, which are certainly to he 



Sttrsirlliilae. 



