384 DISCOVERY REPORTS 



it may well be that it is the larva of T. armatum, since the posterior spine on the abdominal 

 process may perhaps persist as the spine present on somite 3 in the adult. 



Coutiere (1905, p. 21) has described a larva, Caricyplnis aciihts Cout., which he gives 

 reasons for identifying with Tozeiima. This supposition can now be dismissed, since 

 his larva is totally unlike that here described, the identification of which cannot be 

 doubted. 



CHORISMUS ANTARCTICUS PFEFFER 



The plankton collected by the 'Discovery' and the 'William Scoresby' in the 

 neighbourhood of South Georgia contains larvae of three species of Caridea. Of these 

 one cannot be identified ; but the other two belong to Crangon antarcticus Pfeffer and 

 Chorismtis mUarcticiis Pfeffer, the former being the commoner of the two. 



In Chorismiis ontarcticiis the eggs are large, 1 7 x 1-3 mm. I have not seen any eggs at all 

 near hatching, but in one specimen they were sufficiently far advanced for the structure 

 of the embryo to be made out without much difficulty. Rudiments of the full number of 

 appendages were present, and the telson could be seen to be deeply cleft and apparently 

 with 7+7 spines. The telson of the first free larva diff^ers both in shape and in number 

 of spines, so that a more primitive form of telson seems to be retained in the embryo. It 

 is usual in the Caridea for the embryonic telson to bear only six spines, and I am not 

 certain that there is an exception in this case. More advanced material should be 

 examined. 



Stage I. Length 6-6-7-5 mm. (Figs. 89-95). 



Rostrum reaching end of antennular peduncle. Carapace with dorsal papilla and 

 pterygostomial spine. Abdominal somites without spines. Telson slightly concave 

 behind, with 10+ 10 spines. Peduncle of antennule unsegmented ; endopod absent. 

 Scale of antenna constricted at end, with one outer seta near end and eight inner and 

 terminal setae crowded together; four distal segments indistinctly marked; flagellum 

 longer than scale, with basal segment marked oflt; constricted at end into a short 

 denticulate spine. 



Palp of maxillule with five setae, unsegmented. Endopod of maxilla rather large, 

 with three inner lobes ; exopod large, with numerous setae, the seta at proximal end very 

 large; four endites well marked. 



Maxillipede i, endopod of four segments; coxa large; epipod present, bilobed. 

 Exopods of maxillipedes with three apical setae, those of maxillipedes 2 and 3 with 

 twelve and fourteen lateral setae respectively. All legs present, large, legs 1-3 with 

 exopods without setae. Legs i and 2 with rudimentary chelae. Five pairs of pleuro- 

 branchs present. 



Pleopods absent, or present as very small papillae. 



