8b Canadian Arctic Expedition, 191S-18 



along the distal half of the margin of the telson. In N. americana, the number 

 of small spines to the interspace does not exceed three, and they are very in- 

 differently grouped, one, two, or three between any two large spines. Moreover 

 the antennal peduncle of A^. americana is relatively longer, extending from one- 

 third to one-half the length of its terminal joint beyond the second segment of 

 the antennular peduncle; and the antennal scale is shorter and stouter, being 

 less than ten, " about nine times as long as broad " and exceeding the antennular 

 peduncle by less than half its length. In A^. andersoni the antennal scale exceeds 

 the antennular peduncle by more than half the length of the scale. 



From the same station there are numerous immature individuals which 

 have the same general appearance as the adult form described above, and simi- 

 larly proportioned. The distal half of the telson, however, is more attenuate; 

 the spines fringing the tip are subequal, while those on the lateral margins are 

 more or less irregularly large and small, usually two or three small ones between 

 each of two larger ones. This difference, I think, is due rather to immaturity 

 than to a possible difference in species (cf. Mysis oculata, adult juvenile, G. O. 

 Sars, I.e.). 



EUPHAUSIACEA 



Thysanosesa longipes Brandt. 



Hansen, Proo. U. S. Nat. Mus., 48, 87, pi. I, figs. 3a-3d, pi. II, figs, la-le, 1915. 



Station 67 a: Cape Smyth (point Barrow), Alaska,- August 8, 1916. 

 Pelagic, over about 1 fathom of water. 

 1 9, 1 juv., 1 fragmentary specimen. Taken in company with 

 Thysanoessa inermis. 



Thysanoessa inermis (Kr^yer) 

 Hansen, Proc. U. S. Nat. Mus., 48, 93, pi. II, figs. 2a-2d, 1915. 



Station 29 / .• 70° 13' N., 140° 50' W., April 4, 1914. 



From stomach of Phoca hispida Schreber. Depth, about 30 

 fathoms. 

 14 (partly digested, sex ?). Taken in company with 

 Thysanoessa raschii. 

 Station 57 a: Cape Smyth (point Barrow), Alaska, August 8, 1916. 

 Pelagic, over about 1 fathom of water. 

 1 9 . Taken in company with Thysanoessa longipes. 



Tliysanoessa raschii (M. Sars) 

 Hansen, Proc. IT. S. Nat. Mus., 48, 9G, 1915. 



Station 27 n: Colhnson point, Alaska, September 20, 1913. 



Pelagic, over about 1 foot of water; 8 inches ice. 

 1 s . Taken in company with Mysis oculata. 

 Station 27 y^: Lagoon at Collinson point, Alaska, October 8, 1913. 



Pelagic, over 2 feet of water. v 



1 s . Taken in company with Mysis oculata. 

 Station 29 / ; 70° 13' N., 140° 50' W., April 4, 1914. 



From stomach of Phoca hispida Schreber. Depth, about 30 

 fathoms. 

 8 (partly digested, sex ?). Taken in company with Thysanoessa 

 inermis. 

 Station 41 u: Bernard harbour. Northwest Territories, end of August, 1915. 

 From stomach of Salvelinus malma W. 

 1 9 . Taken in company with Mysis oculata. 



