Euphyllopoda g.5 



An unusually large (3| cm. to cercopods) female from St. Paul island, 

 Pribilof islands, Alaska. March 7, 1911. W. L. Hahn coll.^ 



9 females (If to 2§ cm. long) with eggs. Northumberland island, North- 

 west Greenland, 1899. Princeton Expedition (Ortman, 1901, p. 145). 



16 specimens (f to 2 J cm. long; females with ripe eggs) Lake on Northumber- 

 land island. Northwest Greenland. August 7, 1901. R. Stein coll. 



Beside these I have examined a great many specimens from Greenland, 

 Iceland, Spitsbergen, Scandinavia, Baeren island, and arctic Eurasia in various 

 museums (see footnote ^ on p. 9). 



General Distribution 



The species is already known from Cape Rutherford, Grinnell land (Sars, 

 1911), and a number of localities on the north, west and east coasts of Greenland 

 (see Stephensen, 1917), Spitsbergen (Lilljeborg, 1877), Iceland (Kroyer, 1847), 

 Baeren island (Lilljeborg, 1877), mountains of Norway (Sars, 1874, etc.), and 

 Sweden (Lilljeborg, 1877), Archangelsk (Linko, 1901), NovajaZemlya (Lilljeborg, 

 1877), and Arctic Siberia (between longitudes 120° and 150° E. (Sars, 1897). 

 It is thus a truly circumpolar form, though in America it has so far not been 

 recorded from between King William island and Labrador and from the western- 

 most of the islands composing the Canadian Arctic Archipelago. (I can find 

 no definite records of it from Labrador.) 



Biology 



The species has been well described and figured, mainly by Sars (see above) 

 who secured fairly young stages (2.2 mm. long) of it. Also Brehm (see biblio- 

 graphy) described still younger stages collected by myself in northeast Greenland, 

 and similar young specimens were collected by Olofsson on Spitzbergen (1918, p. 

 384.) Two larvae (metanauplii) of the same length (about 1-5 mm.) collected 

 on Novaja Zemlya, June 23, 1875, are in the Riksmuseum, Stockholm. In a 

 former paper (1911) I have recorded my observations made in Greenland on the 

 biology of this species, and similar data were obtained during the Canadian 

 Arctic Expedition, except that no stages between the ripe, deposited eggs and 

 young individuals 3 mm. long were found. I have formerly (1911) stated that 

 the nauplius stage seems to be suppressed, or of exceedingly short duration^ in 

 this species; so aU the stages from the egg to the full-grown individuals of both 

 sexes may therefore be considered known. It is a well-known fact, that the vast 

 majority of the specimens observed of this species have been females (see also 

 the records above) ; the males only attain half the size of the females and seem 

 only to appear later in the summer (August), and in very small numbers (see 

 bibliography, Sars, Brehm.). At least in Greenland the females reach a length 

 of 3| cm., exclusive of the 3 cm. long cercopods (Lilljeborg, 1877).' 



Field Notes and Description op Material 



Of the 3 specimens from Teller, Alaska, the largest was only a fragment, 

 but the two others were females, both 12 mm. long to end of telson (supra-anal 

 plate), while the cercopods (caudal filaments) were 9 mm. long. I give here an 

 outline (magnified about 50 times) of the shape of telson (dorsal view) of one of 

 the 12 mm. long specimens; a comparison of this figure (text figure la) with 

 the succeeding, similar ones mentioned below shows the great variation in this 



lit seems as if the occurrence on islands tends towards increasing the size at which nature specimens 

 of both this species and of Branchinecta paludosa (see p. 19) are generally found in the Arctic. 



2 The genus Apus has a well defined nauplius-stage (see Claus, Baird). 



s In the Zoological Museum, Copenhagen, is a 34 mm. long specimen from Iceland, collected on August 

 28, 1906, and in Uppsala Museum a 36 mm. long specimen from Godhavn (Disco), West Greenland. 



