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7. The Sympoda (Part VI. of S.A. Crustacea, for the Marine 

 Investigations in South Africa)*. By the Eev. THOMAS E. E. 

 STBBBINO, M.A., F.E.S., F.L.S., F.Z.S., Fellow of King's 

 College, London, Hon. Member of New Zealand Inst., Hon. 

 Fellow of Worcester College, Oxford. 



THE Sympoda are a group in many ways remarkable. Its bound- 

 aries are at present as sharply denned as any systematist could 

 possibly wish. All known Crustaceans are either clearly Sympoda 

 or clearly not Sympoda. None hover doubtfully on the outskirts of 

 this society. On the other hand, within its limits the relations are 

 highly perplexing. There is so much interlacing of characters, 

 together with so many fine gradations, that any settled standard of 

 classification is difficult to adopt, or if adopted to uphold against 

 reasonable objections. For distinguishing families practical con- 

 venience solicits a choice of external and easily observable features. 

 The widely separated eyes of Nannastacus offered such a character, 

 till the kindred Cumella was found with a single eye. The presence 

 or absence of a distinct telson sets one group of families in a marked 

 manner apart from another group. Yet between the greatly elongated 

 segment in Makrokylindrus and the disappearance of the segment in 

 Bodotria there are not a few intermediaries, so that a comparatively 

 short and narrow telson in Leptostylis leads on through a short and 

 blunt one in Petalosarsia to forms in which the telsonic segment is 

 produced between the uropods, though the produced part is not 

 articulated, and in Eudorellopsis biplicatus, Caiman, this unarticu- 

 lated portion is marked off "by a very distinct transverse groove." 

 In some of the appendages the third or " ischial " joint is apt to 

 disappear. Accordingly its presence or absence seemed likely to be 

 available for classificatory purposes. But this proved disappointing, 

 because, though the joint is often quite definitely present, and some- 



* Parts I. -III. have been published in the " Marine Investigations in South 

 Africa"; Parts IV. and V. in Vol. VI. of the "Annals of the South African 

 Museum." In Part V., pp. 409-418 treat of the Sympoda (olim Cuimicr/i). 



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