.Studit'S uii iiiafiiif Osli-acdils 



4.i 



one, which, Hke the preceding joint, is rather powerful and is to be denoted as a basak-. 

 Distally on the anterior side the protopodite has indications of two endites. Distally of 

 these and in front of the part that has just been termed the exopodite there is a rather strong, 

 but short and unjointed, process, furnished with powerful muscles and bristles, a process which, 

 on account of its position, is perhaps to be regarded as homologous to the process in the 

 family Polycofidae that was termed by me above the endopodite; cf. fig. IV: 6. The morpho- 

 logical value of this last part seems to me, however, rather doubtful. Does it perhaps belong 

 to the protopodite or the exopodite? 



The families Cypridae, Danvinvlidae, Nesideidae, Cytheridae and Cytherdlidae: In these 

 families the fifth limb shows such far-reaching agreement with the same limb in the Halucypridae 

 that one can show with a fair degree of certainty which parts of this appendage in these families 

 correspond to the different parts of the same organ in the last-mentioned group. 



Cypndat; Darwin- 



ulidac, Nesideidnc. 



Ci/theridae and 



CylherelUdac. 



Fiir. V. — Position of llic vibi-atoiy plair <in liic rillli and sixlli iiiiilis. 1. l-'illh liinl) i>\ Srkrochilua contuHu-s 

 (A. M. XoitMAN). ?. -1. Sixtl\ lirnli (d' Ni-^idoa frcqitens (O. VV. Mi'LLKii) (Kroiii C. W. Millkh. 1894). 



The vibratory plate, which is more or less completely reduced in tiic C \- t li v. v i d s and 

 a number of C y p r i d s, is certainly homologous with the same organ in the H a 1 o c y- 

 p r i d s and, according to the explanation made use of above, it is consequently to be 

 denoted as an epipodial appendage. It is situated at different jilaces on thr protopodite, some- 

 times distally*, sometimes proximally (cf. the accompanying fig. \': 1). The protopodite is 

 unjointed. Distally anteriorly it has sometimes an unjointed process pointing forwards and 

 inwards, which, according to its position, is to be considered homologous to the part that 

 was denoted as the endopodite in the preceding family. This part is in most cases more or 

 less completely absent in Nesideulae and Cytheridae. The backward pointing, rod-shaped. 



* Tlie singly liiisllc (jii llif iiustt-rior side ol' tlie protopodite »r this iiiid) in some C y prids (see fig. 1\ : Ti 

 lias ueilainly been explaineil liy me as a reduied fonn of the vil)ratory plate, but this assumption is. however, far 

 from certain. This uncertainty is jierhaps best illustrated by the sixth limb o\ Cyl/ierella S ; ou this we find on the 

 posterior side of the protopodite not only a well -developed vil>rat<>ry plate, but also some sinirle bristles. Cf.. f'-r 

 instance. C. .<„rdid(i. O. \\ . M) i i.Ei;. I80'i. |>I. 3i. fit,'. 5. 



