CRUSTACEA DEOAPODA— BORRADAILE. 89 



Family CRANGONIDAE. 



19. Crangon {Notocrangon) antarcticus, Pfeffer, 1887, var. gracilis, n. var. 



Crangon antarcticus, Pfeffer, Jahrb. Hamburg.«Wiss. Anst., IV, p. 45, pi. I, figs. 1-21 (1887) ; 

 Ortmann, Proc. Ac. Philadelphia, 1895, pp. 177, 181, 190; Coutiere, Bull. Mus. Paris,' 

 XVI, p. 240 (1900); Caiman, Rep. Nat. Antarctic Exp., 1901-4, Nat. Hist. II, Crust. 

 Decap. p. 3 (1907) ; Lenz and Strunck, Deutsche Sudpolar Exp., XV, iii, p. 324 (1914). 



Crangon (Notocrangon) antarcticus, Coutiere, C. R. Ac. Sci. Paris, CXXX, p. 1640 (1900). 



The affinities of this shrimp are of considerable interest, in view of the support 

 which its distribution has been held to afford to the theory of bipolarity. There can be 

 no doubt that it is more nearly related to the species of Crangon than to those of any 

 other genus of Crangouidae. The resemblance in habit of body to the deep-water 

 species of Pontophilus, noticed by, Coutiere, is purely superficial, and is not really very 

 striking. The small gill-formula (5), the long second leg, the broad stylocerite, and 

 the stout, narrow rami of the pleop&ds, with only the basal projection left to represent 

 the endopodite of the second pair in the male, are enough to separate C. antarcticus 

 widely from Pontophilus. No near relationship to any other genus, save to Crangon, 

 can well be suggested, in view of the condition of the legs, gills, armature of the 

 carapace, and eyes. Within the genus Crangon, the Antarctic species has been 

 supposed by Ortmann to be most nearly related to the Californian C. franciscorum, a 

 member of the typical sub-genus, but Caiman has shown that this view is negatived by 

 its gill-formula and the strong sculpture of its carapace. From its nearest geographical 

 neighbour, C. capensis, Stm., also a member of the typical sub-genus, it is still further 

 differentiated by the absence in the Cape species of the lateral spines on the carapace. 

 On the whole, its affinities would seem, in view of its loss of the arthrobranch of the 

 third maxilliped, and the strong sculpture of its carapace, to be with Sclerocrangon, 

 rather than with Crangon, sensu stricto. It is not possible, however, to place 

 C. antarcticus in Sclerocrangon. The presence of only one spine on the median keel of 

 the carapace is not much more than a technical objection to this course, but the 

 peculiarity of the second pleopod of the male is a more serious obstacle. In this 

 respect the Antarctic species differs also from the sub-genus Crangon. Nor is its habit 

 of body altogether that either of Crangon or of Sclerocrangon, while in the combination 

 of a simple but salient arrangement of ridges and spines on the carapace with a smooth 

 abdomen it is intermediate between the two sub-genera. The best solution of the 

 problem of expressing its affinities in the terms of Systematic Zoology is that of 

 Coutiere, who has proposed to institute for it a new sub-genus, Notocrangon. The 

 facts suggest that the common ancestor of Crangon gave rise on the one hand to 

 Crangon s. str., and on the other to a stock from which Notocrangon has departed less 

 far than Sclerocraiigon. On the face of it, this theory lends some support to the 

 hypothesis of bipolarity, though that is of course not its only possible explanation. 



The " Terra Nova " specimens belong undoubtedly to the form described by 

 Caiman from the same part of the Antarctic. All the peculiarities mentioned by 



