TANAIDACEA AND ISOPODA— TATTERSALL. 233 



Occurrence. — Cumberland Bay, South Georgia, December, 1913, 0-15 fathoms, 

 collected by P. Stammwitz, two males, 57 and 62 mm., one female, 59 mm., and 

 twenty-one juvenile, 12-35 mm. 



Stromness Harbour, South Georgia, January, 1914, collected by P. Stammwitz, 

 one male, 52 mm. 



41a. Glyptonotus antarcticus, Eights, var. acutus, Richardson. PL IX, figs. 3, 4. 



G. acutus, Richardson, 1906 (2), p. 10, pi. I, figs. 2-4; Hodgson, 1910, p. 4-5, pi. VII; 

 Richardson, 1913, p. 17 ; VanhoflFen, 1914, p. .527. 



Occurrence. — Station 220, off Cape Adare, mouth of Eobertson's Bay, 45-50 fathoms, 

 bottom fauna, one female, 86 mm., one male, immature, 62 mm., one cast shell and 

 three juvenile, 8 mm. 



Station. 316, off Glacier Tongue, about 8 miles N. of Hut Point, McMurdo 

 Sound, 190-250 fathoms, bottom fauna, one immature, 26 mm. 



Station 355, 77° 46' S., 166° 8' E., 300 fathoms, bottom fauna, three immature, 

 18, 39 and 53 mm. 



Station 356, off Granite Harbour, entrance to McMurdo Sound, 50 fathoms, bottom 

 fauna, six immature, 20-56 mm. 



March 1, 1911, washed up on North Bay, one male, 99 mm. 

 ,, 29, 1912, trawl in North Bay, one male, 92 mm. 



Remarks. — The differences between these two supposed species are difficult to 

 translate into words. They are differences of degree rather than differences of structure. 

 Eichardson (1906) says that in G. antarcticus Ah.% body is less than twice as long as 

 broad, the metasome shorter than broad and its extremity obtusely pointed ; while in 

 G. acutus the body is two and a half times as long as broad, the metasome longer than 

 broad and its extremity prolonged into a very acute point. CoUinge says that 

 G. antarcticus differs from G. acutus in its more ovoid form and shorter metasome, 

 which terminates much less acutely. These differences in the proportions of the body 

 and of the metasome simply hinge on the degree of prolongation of the extremity 

 of the metasome. It should be remarked at the outset that Miss Eichardson's 

 statements of the dimensions of the two species are somewhat erroneous. From 

 measurements of her own figure of G. acutus, I make the length only 2 • 2 times the 

 breadth ; and according to Pfeffer's figure of G. antarcticus, which is one of the authorities 

 for Miss Eichardson's remarks on that species, the metasome is 1*16 times as long 

 as broad. 



The collections I have examined contain both species at all sizes from about 20 mm. 

 upwards, and from a series of measurements I have made, it is clear that the proportions 

 of the length to the breadth vary with age in both species. The young specimens are 

 proportionately longer than broad, and in both species the metasome is more pointed 

 and produced in young specimens than in old. 



In a series of G. antarcticus, twenty-two in number and varying in size from 



2 L 2 



