sixth and .s e v e n t li limbs is that which is put forward above and 

 called the first in e t li o d of e x p 1 a n a t i o n. It is perhaps best illustrated 

 by the fig. IV given above. 

 Some general A few more words may be added here with regard to the three posterior limbs in the 



remarks about the families Halocypmlae, Cypridae, Darwimdidae, Nesideidae and Cytheridae. 

 tree pos prior i t w. ^^ ^^ mentioned above, almost all writers assume that in the Crustacea, the rod-shaped 



limb has always or almost always arisen from the biramous type by a reduction of the exopodite ; 

 upon this reduction the endopodite became — according to a number of writers — ,,was es am 

 Blattbein war: zur direkten Fortsetzung des Protopodites" (W. GiBSBRECHT, 1913, p. 32). If 

 the explanation adopted by me above is correct, the fifth, sixth and seventh limbs of the five 

 families mentioned above would thus form an important exception to a general rule. (It is, 

 however, to be noted that in the case of the limbs of Leptostraca J. Thiele, 1905, p. 449 

 arrived at a result similar to that obtained by me above; this investigator writes (loc. cit.): 

 ,,Die iibrigen Korperanhange : vorn die vordere Maxille, die Mandibel und die hinteren Antennen. 

 hinten die beiden letzten Pleopoden haben den einen ihrer beiden Aste verloren, an den vorderen 

 Anhangen wahrscheinlich den iiuBeren. an den hinteren vielleicht den inneren, etc."). This 

 cannot, however, be considered surprising by those who, like myself (p. 24), take the view that 

 there was probably no far-reaching morphological difference originally between the different 

 parts of the limbs in Protostraca. 



In exceptional cases the rod-shaped limb would have developed directly from the folia- 

 ceous type. (Even in these cases the distal part of the limb would be homologous with the 

 endopodte). As examples of such a development W. Giesbrecht, 1913, mentioned, as is seen from 

 p. 24 above, the rod-shaped fifth, sixth and seventh limbs in the five Ostracod families just 

 mentioned. This assumption of Giesbrecht's must be regarded as very problematical. It is. 

 of course, connected with this author's homologization of the vibratory plates on these limbs 

 with the exopodites. If we accept my view that this organ is of an epipodial nature, the 

 problem is obviously different; at least for the present it seems best to leave this assumption 

 out of consideration. 

 (■„,,„ inior;/ :.r-;aiis. C o p u 1 a t o r y o r g a n s: — 



I was doubtftd as to the terms I should use for the male copulatory organs in the 

 C y p r i d i n i d s. 



We know that in this group the two vasa deferentia unite distally and open on an unpaired, 

 papilla-like little swelling situated medio -ventrally somewhat in front of the furca. On both 

 sides of this papilla there issue two more or less extensive appendages, in most cases bifurcated 

 distally; these are the organs of copulation. These two organs do not include any part of the 

 ducts of the sexual organs; they are nevertheless called penes by (J. Claus, G. W. MOLler and 

 others ; no special reason for this terminology is given. A. Ramsch , 1906, most fi-equently calls them 

 penes, sometime genital limbs. On the other hand A. GarbINI, 1887, calls these organs „zampe 

 sessuali"; only the small papilla on which the sexual ducts emerge is called penis by this writer. 



If the state of affairs had been the same in other Ostracod groups as in the C y p r i- 

 d i n i (1 s it would undoubtedly have been most convenient to denote the small median 



