558 



TACH SKOC.SIiKUC. 



Fig. CXI. 



(listiillv witli stroiio; bristles; tlicv ;ut situatod almost at ripht angles td cacli (itiicr, the first 

 I'lulit*' points soiiu'what fonvaril and inward, backward and outward, tlio second cnditc sonicwliat 

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

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

 section through the left ma.xilla. i'lic endite on the coxale is not inconsiderably larger than the 



one on the jiroco.xale and is weakly bifurcated distally. (This 

 bifurcation has been taken by several of the preceding writers 

 as a sign that this endite Ims aris(>n from the junction of two. 

 It is difficult to decide hdw lai- this assumption is justified; there 

 are no transitional forms; the assumption, which is obviously 

 based on the fact that in the Cypridini formes 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 powerful, moderately long but broad and rather 

 considerably compressed at the sides. The end joint is rather 

 Horizontal section small, moderately strong and varies somewhat in shape. 

 through a maxilla of a form belong- Por the differences between preceding writers' ideas 



ing to the family Halocypridac: x. ^ ^\ ■ ^ i ^.i ■ \- i i i.u ^ • l, 



diatrrammaiic about the vanous 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 during 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 ventrally 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 inw^ard and developed anteriorly as a powerful 

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

 Piotopodite: 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 



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

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

 1890 a, but without any reasons being given. 



** In a number of forms (see, for instance, fig. 27 of Conchoecia si/mmetrica) one can sometimes distinguish distaliy on 



the endopodite a more or less well-developed chitinous fold. Is this to be explained as the ivmiins of a divisiini into joints? 



* '* I.i |il. VI. fi?. :!. Vt. W. Mui.i.KR, 1906 a, theexopoditeof the fifth limb of Thaamatocypris is drawn willi four join Is. 



