studios on m;iriii(' Osli'iiiods 



;};■) 



vibratory plate may certainly seem, at first sight, to support the assumption tliat we are also 

 concerned with an epipodial appendage in the case of the maxilla in these groups. This arguincnt 

 will, however, count very little with those who take the same view with regard to the morpho- 

 logical value of the different parts of the limbs in Protostraca as that given above on p. 24. 

 The situation and function of the vibratory plate support the assumption that we are concerned 

 with an epipodial appendage; in the C y p r i d i n i d s, in addition, there is often, as we have seen 

 above, an appendage which is situated at about the corresponding place on the maxilla and 

 whose epipodial nature seems to be quite certain. 



In short it seems to me at present quite impossible to find any more decisive proofs 

 for the real morphological value of the different parts of the maxilla in the C y p r i d s, 

 Darwinulids, Nesideids and Cytherids. Under these circumstances would it 

 not be best to accept the terminology used by the majority of the later writers on this subject? 

 This would perhaps have been most correct. I have, however, allowed my personal opinion to 

 prevail in this matter. The homologization adopted by me differs in one important point 

 from that of previous authors: I take the vibratory plate on this limb too as an e})i- 

 podial appendage. In accordance with the view taken by previous writers I look upon the 

 distal part of this limb as an endopodite. It seems to be rather probable that this explanation 

 is correct. At any rate the possibility that it is right must be considered as an open question. 



In the case of the maxilla of the Cytherellidae too the difficulty of carrying out a certain 

 homologization of the different parts is very great. The proximal part with its three endites 

 may very well correspond to the two proximal joints of the protopodite, the procoxale and 

 the coxale. There is the same uncertainty with regard to the palp and the vibratory plate as 

 there is in the case of these organs in the Cyprids, Darwinulids, Nesideids 

 and Cytherids. It seemed to me most convenient to adopt the homologization 

 accepted above for these four groups in the case of the first-mentioned group as well. 



The explanation of the two appendages situated distally on the basale of the maxilla 

 in the family Cypridinidae as an exopodite and an endopodite has already been made by 

 C. Glaus, 1865. This author writes concerning the exopodite (loc. cit. p. 151): ..Jedoch geschieht 

 hier" (W. Liljeborg, 1853) ,,des schmalen .Vnhanges keine Erwahnung, welcher bei unserer 

 Art an der Spitze drei Borsten trjigt unci dem am ersten Maxillenpaare von Cypris und Gythere 

 machtig entwickelten ,Kiemenanhang' zu entsprechen scheint." Tlie vibratory plate, „Kiemen- 

 anhang" on the maxilla of Cypris and Cythere is explained b}' this writer as an exopodite. 

 C. Glaus based this homologization especially on the important fact that in young larvae ,,noch 

 ira Brutraume des Mutterthieres" these two appendages are developed more similarly (cf. 

 G. Glaus, 1865, p. 150, pi. X, fig. 6) and that it is only later on that the endopodite grows stronger 

 in proportion to the , .appendage". A similar opinion is expressed by G. 0. Saks, 1887; he 

 identifies this process with the ,,saakaldte Branchialplade"* in the C y p r i d s ami G y t h e- 

 rids; he does not, however, give any reasons in support of this view. On the other hand 

 G. W. MtlLLER, in his work of 1890, has an explanation of this limb in the family Cypridinidae, 

 which differs exceedingly from that adopted in the present work. This \vriter describes the 



• This wiiter oxprcsswi no opinion as to Iho morpliolotriial inlcrprelation of this .,[5ran<hialplade" {hraiic-hial plale). 



Cytherellidae. 



Historical. 



