558 



TAGE SKOGSBERG 



arn/. 



distally with strong bristles; tliey are situated almost at right angles to each other, the first 

 endite points somewhat forward and inward, backward and outward, the second endite somewhat 

 forward and outward, backward and inward; their relative positions and orientation in relation 

 to the endopodite will be best seen from the adjoining diagram, fig. CXI, representing a horizontal 

 secticm through the left maxilla. The endite on the coxale is not inconsiderably larger than the 



one on the procoxale and is weakly bifurcated distally. (This 

 bifurcation has been taken by several of the preceding writers 

 as a sign that this endite has arisen from the junction of two. 

 It is difficult to decide how far this assumption is justified; there 

 are no transitional forms; the assumption, which is obviously 

 based on the fact that in the Cypridiniformes this limb has in 

 most cases three endites on these two joints, seems to me, 

 however, not improbable.)* The basale has no trace of any 

 endite. Endopodite: The first joint is comparatively 

 large and j^owerful, moderately long but broad and rather 

 considerably compressed at the sides. The end joint is rather 

 small, moderately strong and varies somewhat in shape. 



For the differences between preceding writers' ideas 

 about the various parts of this limb and that given above 

 see p. 34 above. 



Fifth limb: — This varies rather slightly within this group. It seems to serve 

 chiefly as an organ for holding the food fast dui'ing mastication and for carrying the food to the 

 mouth, and perhaps as a masticatory organ, too; in addition it also seems to serve as a climbing 

 organ. It is situated on the side of the body just behind the maxilla, at the boundary between 

 the hypostome and the anterior part of the body. It is always rather large and has comparatively 

 powerful musculature. It consists of a ventraUy pointing protopodite, which is rather volu- 

 minous, comparatively elongated, unjointed or in exceptional cases more or less indistinctly 

 two-jointed, and which is not or only rather slightly larger than the exopodite, a moderately 

 large epipodial appendage developed as a vibratory plate, a very short, but rather powerful, 

 unjointed** endopodite, pointing forward and inward and developed anteriorly as a powerful 

 endite and a rather large and elongated backward pointing exopodite with three or four joints.*** 

 Protopodite: In those cases in which this has two joints the boundary between the two 

 joints is often rather weakly developed and difficult to distinguish with certainty; the proximal 

 joint seems to correspond to the coxale or possibly the procoxale + the coxale, the distal joint 

 to the basale. The proximal part, the coxale in the forms that have a two-jointed protopodite, 

 is rather closely joined medially to the body and has no bristles at all. The distal part, the basale 



Fig. CXI. — Horizontal section 

 Ihrougli a maxilla of a form belong- 

 ing to the family Halocypridne; 

 diagrammatic. 



* On the other hand it seems impossible to decide which of the two processes corresponds to the original second 

 e.idite and whicli is homologous with the original third endite. This has been done, however, by G. W. Muli.er, 

 IX'.tOa, but williout any rea.sons being given. 



** 1:1 a number of forms (see, for instance, fig. 27 of Conchoecia sijinmelrica) one can sometimes distinguish distally on 



thr endapodite a more or less well-developed chitinous fold. Is this to be explained as the remains of a division into joints? 



* ** 111 |fI. VI. fi'j^. ;!. G. W. Mil 1,1, I'll. lOiir, a. till' cxcipdililc (it llic fiflli liinliof Tliaiiiiiiitort/pri.-: is drawn with four joints. 



