410 Annals of tlie South African Museum. 



with the two previous ones, Parisoclachis and Spha&ramene, appear 

 to represent a third section of the Hemibranchiate Sphaerominae, 

 equal in value to Hansen's Sphaeromini and Cyrnodocini. This 

 section is intermediate between the Hemibranchiatae and the 

 Eubranchiatae, combining the pleopods of the former with the 

 telson of the latter. Within the section, Parisocladus and Sphaera- 

 mene are nearer the typical Hemibranchiatae in having a 2- jointed 

 outer ramus to pleopod 3, while Dynoides is nearer the Eubranchiatae 

 in having the outer ramus of pleopod 3 un jointed. 



GROUP EUBEANCHIATAE, Hansen. 



Gen. DYNAMENELLA, Hansen. 



1905. Dynamenella, Hansen, Q. J. Microsc. Sci. vol. 49, pt. 1, 



pp. 107, 126. 



1905. Eichardson, Bull. U.S. Nat. Mus. No. 54, p. ix. 



1906. id. Proc. U.S. Nat. Mus. vol. 31 (1907), p. 14. 



1907. Nobili, Mem. Ace. Sci. Torino (2), vol. 57, 



p. 422. 



Hansen gives as one of the characters of this genus " without real 

 processes," and Miss Eichardson accepts this (I.e. 1906, p. 14). 

 However in the type species D. perforata (Moore) the 7th peraeon 

 segment is produced backward in 2 rounded lobes (Eichardson, 1905, 

 I.e. p. 300, fig. 319). To a less extent the same is the case in 

 D. australis, Eichardson, and D. scabricula (Heller). There seems 

 therefore no reason why D. dioxus, n. sp., should not be included 

 in the genus, at least for the present ; and this I have done. To 

 the definition of the genus thus modified namely, 7th peraeon 

 segment with or without processes in $ can be added : mouth 

 parts in $ not modified, brood developed in internal pouches. 



The terminal notch is variable, being sometimes of the same width 

 throughout, sometimes widening anteriorly into a foramen, but it is 

 always similar in both sexes, though often rather deeper in the $ 

 than the $ . The cordiforrn shape of the aperture in D. dioxus, n. sp., 

 invites comparison with D. platura, Nobili (1907, I.e. p. 423, pi. 2, 

 fig. 12), and Cymodocea cordiforaminalis, Chilton (1882, Tr. N.Z. Inst. 

 vol. 15, p. 188, plate 22a, fig. 1). The two last-mentioned species in 

 fact appear to be very closely allied if not actually identical. The 

 figure of the telson of the female which Nobili gives (fig. 12a) may 

 very possibly be that of an immature specimen in which the apical 

 notch has not reached its fulldevelopment. 



