702 General Notes. [July, 
compressed body with lamellate gills on the thoracic feet and an 
elongated abdomen, of which the three anterior segments bear 
the swimming feet, while the three posterior has posteriorly directed 
feet adapted for springing (Claus). Now if Acanthotelson is not 
an isopod, still less should it be regarded as related to the Amphi- 
poda. The first antenne are entirely unlike those of any known 
amphipod, in which there is a very short accessory flagellum ; the 
second antenne of Acanthotelson are strictly decapodous in ap- 
pearance and very different from that of the Amphipoda, whereas 
in Gammarus the scape is as long as the flagellum. Although 
there are seven free thoracic segments in Acanthotelson as well 
as in Gammarus and other Amphipoda, those of Acanthotelson 
pods is still more marked. The first five pairs of uropoda or 
abdominal appendages are in Acanthotelson all formed apparently 
on the same plan, not essentially different from those of schizo- 
pods, while the last pair are flat and on the same plane as the tel- 
son and intimately associated with the latter, in that these parts 
are formed on a truly macrurous plan and most approach those 
of the schizopods, in which the telson and rami of the last pair 
of feet are narrow and more or less acute at the end. There is 
nothing in the structure of the urosome and its uropoda in Acan- 
_ thotelson to remind us of the same parts in the Amphipoda. 
ae homologous with those of these two groups. The Syncarida, 
n their lack of a carapace and in the well-formed dorsal arch 
the seven thoracic segments, we are obliged to consider as 
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