ENTOMOSTRACA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 327 



Fam. ASTEROCHERID/E. 



Genus Asterocheres, Boeck, 1859. 

 Asterocheres suberites, Giesbrecht, var. antarctica, nov. var. (PI. VI. figs. 3-11.) 



Like Asterocheres suberites, Giesbrecht, in general appearance. Length, "94 mm. 

 Antennules composed of twenty-one joints, moderately elongated and slender ; first 

 joint stouter and longer than any of the others, the second to the eleventh very short, 

 especially the last two ; each joint is also somewhat narrower than the one that precedes 

 it ; the twelfth to the eighteenth are of moderate length and subequal, the three end 

 joints rather small, but the penultimate one is somewhat longer than either of the other 

 two. The formula shows approximately the proportional lengths of the various joints : 

 Number of the joints 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 



Proportional lengths of joints 2143333332 3 5777899454 



Antennae moderately slender and armed with a long claw-like spine ; the first and 

 fourth joints short, the second and third elongated ; outer ramus small, uniarticulated, 

 and bearing two or three short terminal bristles (fig. 3). 



Siphon short, somewhat triangular ; mandibles styliform ; maxillae and maxilli- 

 peds nearly as in A. suberites, Giesbrecht. 



The four pairs of swimming legs also resemble those of the species named. The 

 fifth pair are very small and uniarticulate. The caudal furca are rather longer than 

 the last segment of the abdomen, and about equal to the length of the penultimate 

 segment (fig. 11). 



Habitat. Scotia Bay, South Orkneys, June 1903; Station 325, 60 43' 42" S., 

 44 38' 33" W. 



Remarks. The species recorded above so closely resembles Asterocheres suberites, 

 Giesbrecht, as to be scarcely separable from it. There is a slight difference in the form of 

 the siphon ; the outer marginal spines of the exopods of some of the swimming feet are 

 stouter, and the fifth pair of feet are distinctly smaller. One or two other slight differ- 

 ences may be observed, as, for example, in the proportional lengths of the joints of the 

 antennules, and of the abdominal segments, but this Antarctic form can scarcely be 

 regarded as more than a variety of A. suberites. 



Fam. ARTOTROGID.E. 

 Genus Artotrogus, Boeck, 1859. 

 Artotrogus jiroximus, new species. (PI. XI. figs. 1-9.) 



Description of the Female. The outline of the female, seen from above, is sub- 

 orbicular ; the cephalothoracic segment is greatly expanded, and forms the largest 

 portion of the animal ; the remaining thoracic segments are comparatively small ; the 

 abdomen is also small, but the genital segment of the abdomen is larger than the other 

 segments, and is produced backwards on each side so as partly to enclose them, as 



(ROT. soc. EDIN. TRANS., VOL. XLVIII., 573.) 



