CEUSTACBA. 



I-DECAPODA. 



By W. T. Calman, D.Sc. 



Two species of Decapod Crustacea were obtained by the ' Discovery ' within the 

 Antarctic Circle. They have been identified with the two species collected by the 

 German Polar Commission of 1882-1883 at South G-eorgia. By the courtesy of Dr. 

 Georg Pfeffer, of the Hamburg Museum, who first described the species, I have been 

 able to compare the ' Discovery ' specimens with co-types from South Georgia, and to 

 satisfy myself of their identity. AVith the circumpolar range implied by their 

 occurrence at these two widely separated points, both species combine a remarkable 

 range in depth, for, whereas at South Georgia they were found at 7-9 fathoms, the 

 ' Discovery ' dredged both species at depths reaching to 500 fathoms.* Dr. PfefFer's 

 descriptions, although very detailed and accurate, leave unnoticed certain characters 

 which are now regarded as of systematic importance. I have, therefore, found it 

 necessary to supplement his account on some points. One of the species, Crangon 

 antarcticus, has received some attention in recent discussions on the subject of 

 " bipolarity," and I have therefore attempted to define a little more precisely its 

 afiinities with related forms. 



FAMILY HIPPOLYTlDiE. 



Chorismus antarcticus. 



Hippolyte antarctica Pfeffer, Jahrb. Hamburg. Wiss. Anst. IV. (1887), p. T)!, pi. i. figs. 22-27. 



Description of ovigerous females. — Total length 87 to 101 mm. Length of carapace 

 (including rostrum) about two-fifths of total length of body. Rostrum equal to or a 

 little longer than the distance from the orbital notch to posterior margin of carapace 

 in the middle line, curved upwards, moderately expanded below ; upper margin with 

 eight or nine teeth, of which the second is placed over, or a little in front of, or 



* Crangon antarcticus was also dredged by the ' Belgica ' at a depth of 400-500 fathoms in Lat. 71° S. , 

 Long. 88" W. 



