No. 4-] NORTH-AMERICAN ECHIURIDS. 175 



its habits, so far as observed, correspond exactly with those just 

 given. Its burrow is horseshoe-shaped, the two ends opening 

 at the surface, and around each is a little mound formed by the 

 pushing aside of the mud. The iron ingredients of the mud 

 in the walls of the burrow are also discolored by the mucus 

 secreted by the animal and show as a rusty brown. 



In size the Alaskan specimens surpass those from Casco 

 Bay, and the same shovelful of mud often reveals giants and 

 pigmies of the species side by side. But this is simply in 

 accordance with the general results of the expedition, for gigan- 

 tic specimens of nearly every native species were found. 



The number of setae in the anal rings of four specimens 

 selected at random were counted. In three of these there 

 were eight setae in the anterior ring and seven in the posterior, 

 but in the fourth specimen the numbers were nine and eight 

 respectively. 



The fact that specimens from two such widely separated 

 localities agree perfectly in carrying the maximum of size 

 beyond 30 cm. and also in the variation of the number of setae 

 in the anal rings, is a third argument, and quite a strong one, 

 against the validity of the species forcipatus. 



There seems to be no discernible connection between the 

 number of the setae in the anal rings and the size of the ani- 

 mal ; a small specimen is just as likely to possess the larger 

 number. 



On the contrary, there is something of a connection between 

 the size of the individual and the temperature of its environ- 

 ment ; in general, the colder the water the larger the average of 

 the species. Such a fact strongly corroborates the statement 

 made by Shipley (14) that "this genus is a denizen of the 

 colder seas," and indicates that an Arctic environment is most 

 congenial to its development. 



These two new localities also go far toward rendering this 

 species cosmopolitan. It has already been reported from the 

 North Sea, where it was originally discovered, the English 

 Channel, and the coasts of Norway, Sweden, Denmark, Hol- 

 land, and Belgium. To these can now be added the American 

 North Atlantic and North Pacific, and it may be expected as 



