. k Text-fig. 17. Arcturides acuminatus (a) Maxillula (left), x 25. {b) Tip of uropod. (c) Dorsal view of pleotelson. ((i) Maxilla (right), x 15. (e) First pereiopod, x 20. (/) Maxilliped (left), x 25. (^) Lateral view of female, x 7. (/;) Antenna, X 12. (7) Antennule, x 18. (/:) Second pereiopod, x 20. (/) Seventh pereiopod, x 20. outwards and is about a third of the length of the broader part of the exopodite. In ^. acuminatus, the distal end of the projection is obliquely truncated to form a pointed extremity (Text-fig. i8«); the appendix masculina of the second pleopod (Text-fig. iSc
. k Text-fig. 17. Arcturides acuminatus (a) Maxillula (left), x 25. {b) Tip of uropod. (c) Dorsal view of pleotelson. ((i) Maxilla (right), x 15. (e) First pereiopod, x 20. (/) Maxilliped (left), x 25. (^) Lateral view of female, x 7. (/;) Antenna, X 12. (7) Antennule, x 18. (/:) Second pereiopod, x 20. (/) Seventh pereiopod, x 20. outwards and is about a third of the length of the broader part of the exopodite. In ^. acuminatus, the distal end of the projection is obliquely truncated to form a pointed extremity (Text-fig. i8«); the appendix masculina of the second pleopod (Text-fig. iSc) is about the same length as the endo- podite, its distal end is flattened and terminates in a curved pointed projection. The exopodite and endopodite of the uropod (Text-fig. 176) are of approximately equal size and each is tipped with a single seta. A. acuminatus bears a close resemblance to the genotype A. cornutus Studer and also to a species, A. tribulis, described and figured by Hale in 1946, but differs from them in the following points: (i) The narrow distal extremity of the pleotelson tapers to a point in acuminatus whereas in the other two species it is truncate and notched. (2) In acuminatus the body armature has body spines less well-developed than those of tribiilus, and the blunt, downwardly directed tooth is not present on the antero-lateral angle of the head. (3) In acuminatus the areas above the insertions of the coxal joints are raised. (4) The endite of the maxilliped is also diff^erent. Both Studer's and Hale's specimens were obtained from Kerguelen Island, and Hale suggested that in view of their great similarity tribulis might be a variety of cornutus. Beddard's material of
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