178 CALIFORNIA ACADEMY OF SCIENCES. 



Genus Nectocrangon Brandt. 



Kostrum wanting. Eyes hidden by the carapace. Second pair of pereo- 

 pods chelate; dactyls of the last two pairs dilated and fitted for swimming. 

 Branchise five on each side; none on the second maxilliped. 



Type. — N. lar (Owen). 



Nectocrangon lar (Owen). 



Crangon lar Owen, Zool. Beechy's Voyage, 1839, p. 88, PI. XXVIII, fig. 1.. 



Argis lar Kroyer, Nat. Hist. Tidskr., IV, 1842-3, p. 255, PI. V, figs.. 

 45-62. 



Nectocrangon lar Brandt, in Middendorff 's Siberische Keise, Bd. II, Th. 

 1, 1851, p. 115. Stimpson, Proc. Acad. Nat. Sci. Phila., 1860, p. 25;. 

 Ann. N. Y. Lye. Nat. Hist., Vol. X, 1873, p. 125. Kingsley, Bull. 

 Essex Inst., Vol. X, 1879, p. 55. Smith, Kep. Prog. Geol. ^ur. Can- 

 ada, 1878-9, B, p. 212; Trans. Conn. Acad., Vol. V, 1879, p. 61. 

 Murdoch, Kep. Int. Polar Expd. to Pt. Barrow, 1885, p. 139. Ortmann,. 

 Proc. Acad. Nat. Sci. Phila., 1895, p. 181. 



Median carina of the carapace armed with two spines behind the one at 

 the anterior end. First five abdominal segments with a median dorsal 

 carina, that of the fifth segment ending behind in a tooth or spine; the 

 two carinse of the sixth segment end posteriorly in a small spine. Telson- 

 acute, the carinas armed with two or three pairs of spines near the tip. 



Circumpolar: Arctic Ocean (Owen, Stimpson); Green-^ 

 land (Kroyer); Labrador, Nova Scotia, Vancouver's 

 Island (Smith); Pt. Barrow (Murdoch). 



Owen's statement, that in this species '' the second 

 joint of the superior antenna is dilated and spiniform 

 externally" is an error. He mistook the first joint for 

 the second; the second is cylindrical. 



A specimen in the U. S. National Museum (No. 7889) 

 from Alaska agrees very closely with several specimens 

 I have seen from the Atlantic. The ridges on the cara-^ 

 pace are a little plainer than in the Atlantic forms; the 

 carinas on the abdomen are a little less acute and have a 

 more decided tendency to fade out behind; the carina, 

 of the fifth segment ends behind in a tooth, but those of 

 the sixth segment do not. In specimens from the North. 



