80 TAGE SKOGSBERG 



Are we to accept the homologization carried out by G. W, MUller? 



In answering this question I shall leave the Cypridinids, Halocyprids 

 and Polycopids out of consideration and turn to the groups, on whose number of joints 

 G. W. MUller has obviously based the assumption mentioned above. Macroci/pris, the genus 

 that is considered as the most primitive among the C y p r i d s, is characterized by a four- 

 jointed endopodite. Its second joint is comparatively long and has on the posterior edge, 

 proximally of the middle, one or a couple of bristles, on the anterior edge, near the third joint, 

 two bristles situated close to each other. The third joint is comparatively short and is moved 

 by two muscles, a flexor and an extensor, both with a proximal attachment situated proximally 

 in the second joint; this joint is always armed disto-anteriorly with a number of long, powerful 

 claws. The fourth joint is small, issuing at about the middle of the posterior side of the third 

 joint; it is moved by only one muscle, which has its proximal attachment proximally in the 

 second joint; and it is armed distally with several bristles, one of which is a sensory bristle. 

 In other genera belonging to the family Cypridae the state of affairs is often somewhat different. 

 The postero-proximal bristle of the second joint is almost always lacking, but, on the other 

 hand, this joint almost always has, as in Macrocypris, on the anterior edge two* bristles situated 

 close together; only in exceptional cases does one of these bristles seem to be absent. In some 

 species the boundary between the second and third joints has more or less completely disappeared. 

 In a number of these forms the two muscles which we found moved the third joint in the genus 

 Macrocypris are missing; in others, however, they can be found; distally-anteriorly this joint, 

 as in Macrocypris, always has powerful, claw-like bristles. The fourth joint may be more 

 or less completely reduced in a number of species, but even in those forms in which this joint 

 has quite disappeared it always seems possible to distinguish by their position the bristles that 

 belong to this joint from those that belong to the original third joint, as they are situated 

 distally-posteriorly on the end joint and are separated from the bristles of the original third 

 joint by a swelling in the chitinous wall of the joint; in some forms a distinct gap can also be 

 observed between these two groups of bristles. In the family Nesideidae we find the follow- 

 ing state of affairs: All the three recent genera of this family that have been described so far, 

 Nesidea, Bijthocypris and Anchistrocheles, have a four-jointed endopodite, of about the same 

 type in all of them. The genus Nesidea (cf. G. W. MUller, 1894, pi. XV, fig. 29): The second 

 joint is moderately long and has only one or a few bristles situated postero-distally. The third 

 joint is relatively long; it is not moved by special muscles and has, among other things, two 

 bristles situated close together on the anterior edge a short distance from the distal boundary; 

 distally-anteriorly this joint has no bristles at all. The fourth joint is short and is moved by 

 two muscles, a flexor and an extensor, both having a proximal attachment proximally on the 

 second joint; it is provided with five bristles, which, at least in a number of species, are situated 

 in two groups, as I have had an opportimity of observing myself when investigating a couple 



•) G. W. MuLLER states, 1894, p. 'lO that the C y j) r i d s always have a siiigh' bristle at this phu'e. ,,Das 

 2. Glied lies Iniienastes .... tragt constant eine kh'ine Borste am clDrsalen Rand": two bristles, are, however, drawn 

 in the figvircs of several species belonging to this group that this author has given in this work. The statement made 

 above is based on observations of a large nuinbei- of species investigated by me. 



