4.J2 TAC.F. SKOOSIIRnO 



Willi iv<j;aril tti tin- tlilTi'rciu'rs botwofii (lie pivvious authors' iiitiTprcfiitions of (lio 

 iliffoHMit parts of this limh and that which is followed in tliis work, see above |)p. ,'5.3 and '.id. 



V i t t h I i 111 li: This lias no (or soiiietiiues very sliglit?) sexual (liiiiui|]|iisiii. — |jil<e 

 the ]ireeedin<: liiiili it has a very peculiar type of structure, very dift'ereiil Imm all ntlirr 

 s t r a c o d s; see tig. IN : .">. 'i'lie p r n t o p o d i t e ami the (wo proximal exopodite 

 joints are difTerentiated into a rather long, narrow. toiiguc-slia])ed and (piitc unjoiiitcd organ, 

 strongly coinpressetl from the sides. This organ is bent slightly inward, — in the same way ;is 

 the protopodite of tlie maxilla. — pointing anteriorly and outwards and twisted so that its 

 ventral edge is pointed oblitpiely (lownwards towards the maxilla. Along the ventral edge of 

 this organ there is a dense series of moderately long or more or less short bristles. The distal 

 part of the e x o ]i o d i t e is reduced, being only represented by one or a few bristles, more 

 seldom by a small verruciform j^rocess laterally somewhat in front of the middle of the tongue- 

 shaped organ formed by the protopodite and the two proximal exopodite joints. The e p i- 

 p o d i a 1 appendage is supported by rather powerful chitinous lists, which end dorsally, 

 as they do ventrally. in a strong, spine-like part. The ventral one of these spines forms the 

 end, so to speak, of the tongue-like part posteriorly; it is not free, as one would be inclined 

 to believe from the descriptions of previous writers, but is attached to the wall of the body along 

 the whole of its dorsal side; cf. fig. 14 of A. aberrata. 



With regard to the differences between the interpretations of the different parts of this 

 limb that have already appeared in the literature and that accepted in the present work see 

 above pp. 38 — 42. 



Sixth 1 i m Ik — This has no (or sometimes very slight?) sexual dimorphism. — It is 

 always rather large and rather considerably lengthened in the longitudinal direction of the body, 

 lamelliform, quite unjointed, but in other re.spects it varies considerably in type. 



Seventh limb: — This has no or sometimes very slight sexual dimorpliism. — ■ It 

 has from two to four end combs arranged in pairs. In other respects it varies considerably in type. 



Penis: — This is small and is only weakly chitinized. Distally it is split into two lobes. 



Gills: — These have no or only very slight sexual dimorphism. — Contrary to what is 

 the case in all other known Ostracods* well-developed gills are found in this group. They 

 consist of a number of lamellae, attached along the dorsal side of the posterior part of the body 

 and arranged in two longitudinal rows separated by a narrow space. The lamellae are placed 

 transversely, pointing backwards and upwards and, when the animal is seen from the side, they 

 cover the greater part of the dorsal side of the back of the body. With regard to their fine 

 structure they resemble the lamellae of the gills in the other closely-related Crustacean groups. 



Special (erminology: — First antenna: — The far-reaching resemblance shown 

 by the end bristles, with regard to their number, position and type, to the end bristles on 

 this limb in the family Cypridinidae can only be explained as real homology; on account of 

 this I considered it best to make use of the same notation for this group as for the family 

 just mentioned (cf. remark on genus Asterope, p. 462). 



* Cypridina Hilgendorfi, G. W. Miller, 1890, p. 228 is an exception. 



