CRUSTACEA DECAPODA—BORRADAILE. 
89 
Family CRANGON ID AE. 
19. Crangon ( Notocrangon) antarcticus, Pfeifer, 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, 
XA r I, p. 240 (1900); Caiman, Rep. Nat. Antarctic Exp., 1901-4, Nat. Hist. II, Crust. 
Decap. p. 3 (1907); Lenz and Strunck, Deutsche Siidpolar 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 Crangonidae. 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 pleopods, 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 lie 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 Sclerocrangon. 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. AH the peculiarities mentioned by 
