studies on marine Ostracods 79 



Why does not the proximal, joint-like process represent the first joint of a two-jointed 

 protopodite? Or — if it were to appear that a similar process exists in the genus CythereUa 

 as well, which does not seem improbable, first because of a drawing of this antenna given by 

 G. W. MtJLLBR, 1894, pi. 32, fig. 1, and secondly because of what I have observed myself in 

 a preparation of a similar antenna* — why should we not assume a three- 

 jointed protopodite? This number is as a matter of fact assumed by H. J. Hansen 

 as the original one for all the post-oral limbs of the Crustacea (cf. Z o o 1. A n z. 1893, p. 194). 

 In a new form (not described)**, closely related to the genus Macrocypris I observed that this 

 basal part is composed of two clearly separated segments. Why then might it not be assumed 

 that this process is homologous with the procoxale and the coxale, so that the large joint that 

 follows is homologous with the basale? The formation of a knee would thus in these forms 

 too have taken place between the basale on the one hand and the exopodite and endopodite on the 

 other. As in the case of the mandible of the Cypridinids a ventrally pointing knee would 

 have been developed between the coxale and the basale. Before it has been clearly proved that 

 these homologizations are impossible we cannot accept the view put forward by G. W. Mt'LLER. 



G. W. MUller's assumption with regard to the endopodite of this antenna of the 

 Protostracods seems to me almost equally imfounded. This would resemble most 

 closely this branch in the Polycopids. 



The endopodite would have been four- jointed. According to G. W. MtlLLER's state- 

 ments the recent Ostracods have the following number of joints on this branch. Leav- 

 ing out of consideration forms with a more or less reduced endopodite, the Cypridinids 

 have three joints. Among the Halocyprids the female (the male is unknown) of 

 Thaumatocypris, which is in several respects presumably the most primitive genus, 

 has only two joints; in the other forms of this group we always find in the males more 

 or less distinctly three joints, in the females most frequently only two joints. Tlic P o 1 y- 

 c o p i d s, the group that would possess the most primitive second antenna, appear always 

 to have three joints. The C y p r i d s sometimes have a four-jointed, and sometimes a three- 

 jointed, endopodite; in the cases where a three-jointed endopodite is found the end joint has 

 either more or less entirely disappeared or else the second joint has arisen by a union of two 

 joints; traces of this union can stiU be observed in some forms. Darwimdidae has three joints; 

 the second joint would have arisen by the union of two joints, but there seems to be no traces 

 of this union present; no such traces are at any rate to be seen on figures hitherto published, 

 nor are they mentioned either by G. W. MtlLLER or other writers. Nesideidae is characterized 

 by four joints. The Cytherids have three or four joints — in the cases in which three 

 joints are found the second joint would have arisen by a union of two joints; traces of this union 

 can sometimes by observed. The Cijtherdlidae have three joints; the second of these would 

 show „deutliche" traces of a union (1894, p. 43); no such traces can, however, be found on the 

 figure given by G. W. MULLER (1894, pi. 32, fig. 4), nor have I succeeded in observing any on a 

 specimen investigated by me. 



• The prepaiMtion was unfortuiialoly dofcctive. 

 ** To be published in a following part of this work. 



