:]H TAGE SKOGSBERG 



certain wliether it is to be considered, compared with tlie fifth limb in tlie following family, as 

 a primitively simple one or as having been simplified secondarily; for several reasons the 

 hitter of these two alternatives seems to me the more probable; with regard to this I shall 

 onlv refer to what has been \vi-itten below in the second chapter of this treatise about the type 

 of the fifth limb in the primitive Ostracods.) The exopodite, endopodite and epipodial 

 appendage on this limb are — if this same method of explanation is employed for this family 

 as has just been used for the family Poli/copidae — of types that differ rather slightly from 

 those observed in the Polycopidae. The process that is supposed to represent the exopodite 

 is, however, relatively larger, the endopodite* is small relatively; the joints of the protopodite 

 cannot be distinguished. There is, at least in some cases, an indication of an endite proximally 

 of the process that has been explained as the endopodite (cf. the fifth limb of Sarsiella capsnla 

 A. M. NOKMAN, in Gr. 0. Sars, 1887, pi. X, fig. 8, reproduced below, fig. IV: 2 and G. W. Mi'Ll.ER 

 1894, pi. 4, fig. 28). 



('i/prifliiinhic. Family Cypridinidae (see fig. IV: 3, 4): In this family the fifth limb is both very much 



differentiated and (secondarily?) also of a rather marked foliaceous type. But in spite of its 

 complex structure it shows a fairly great resemblance to the same limb in the families Poly- 

 copidae and SarfiieUidae, especially to the latter. If the homologization carried out above is 

 applied to this family, we have, in my opinion, the following results: The protopodite 

 is powerful and often dominates somewhat over the distal part of the limb; it is in most 

 cases divided into two joints, but sometimes, however, it is three-jointed, the proximal one 

 of these two joints has been divided into two more or less distinct joints; in the latter case we 

 can thus distinguish a procoxale, a coxale and a basale. The protopodite is armed on its 

 inner edge with three endites, in most cases powerful, one on the procoxale, one on the 

 coxale and one on the basale. According to this method of explanation the part situated distally 

 of the protopodite is homologous with the exopodite; it is in most cases four- or five-jointed 

 (four-jointed in the accompanying figure). Of the joints of the exopodite the two proximal 

 ones are in most cases very strongly chitinized; each of them has on the inner edge a powerful 

 endite armed with bristles and teeth. The following joints differ in most cases very considerably 

 from the preceding ones on account of their structure**; they are very slightly chitinized and 

 their bristles are in most cases rather soft and plumous. The fourth exopodite joint is, as 

 a. W. MUller showed as early as 1894, p. 62, sunk deeply in joint no. 3. In this way the 

 latter joint is divided into two lobes, one outer and one inner one; the inner lobe is, in addition, 

 often more or less reduced. The vibratory plate, which, according to this explanation, is to 

 be looked u{)on as an epipodial appendage, has almost exactly the same type and position as the 

 same organ in the family SarsieUidae. The endopodite seems to be always absent in this limb.** 



Asicn.,,„Uw. Family Asteropidae: In this family the fiftli limb shows, as we know, a type that differs 



very nuich from the same appendage in other families; cf. the genus description of Astervpe 



* The intorpretation of this pari seems to me, however, rather uncertain. 

 ** This liil'feriMice ransed me at first to assnnio that the two powerful proximal joints represented llie endopodite, 

 an assnmplion llial si'cmed lo l.c snppnrlr.l liy fi;;. /,, p. CO. G. VV. Muli.kii. 18<.)'. (= my fig. IV: 3). II is, however, 

 pi'esumalily in( Dii'ecl. 



