NORTH ATLANTIC SEA AND THE FAROE CHANNEL. 133 



51° N. Two species, E. norverjica and harhata, are common ; the third, 

 E. glacialis, is rather rare. The first species occurs in so many stages 

 of development that Thompson, who reported upon Fowler's Copepoda, 

 was probably misled. Tliough doubt has been expressed upon the 

 accuracy of the diagnosis of E. harhata, there is no doubt that this 

 is a good species. Each of the three differs, especially in the form 

 of the genital segment of the female, the length of the appendicular 

 tail setffi, the structure of the first and second feet, and the anatomy 

 of the last segment of the fifth foot of the (? , especially in its "scissors " 

 arrangement. What is meant in Thompson's list by E. hessii and E. gigas 

 (Brady) it is difficult to say. At any rate only the three Euchcctas 

 mentioned are as yet known to occur in the Faroe Channel. 



E. norvegica extends southwards into the warm Atlantic area, at 

 any rate, as far south as 51" IST. It is fairly common in the warm 

 area, but not so much so as in the deep water of the Faroe Channel, 

 where it is seldom absent from deep hauls ; it is thus capable of 

 ranging through wide differences of temperature. Though, as I am 

 informed by Sir J. Murray, it is of common occurrence in the surface 

 waters of some of the Western Scotch lochs, I have never seen an adult 

 in the surface area of the Faroe Channel or Atlantic. Young and 

 undeveloped specimens are not uncommon near the surface, but the 

 adult animal appears to prefer the deep water down to 500 to 600 

 fathoms, and to extend northwards to the Polar basin. 



E. glacialis, observed abundantly in the Polar basin (Hansen), but 

 seldom in the Norwegian Sea, is of rare occurrence in the Faroe 

 Channel, and once only it occurred in the warm Atlantic area. 



E. acuta, of which a few undoubted examples were met with in lat. 

 50° 56' and 12° 6' W. long, at 300 fathoms depth, has hitherto had 

 a northern limit of only 41° N. It has lately been recorded by Scott 

 from the Indian Ocean. 



E, harhata, first described by Brady from the South Atlantic (Eio 

 Janeiro), and lately by Scott from Ceylon, occurring with frequency in 

 the Faroe Channel, has thus a very wide range. In the Atlantic it is 

 purely a deep-water species, occurring once at 500 fathoms in lat. 55° 

 47' N. 



These three species {E. norvegica, glacialis, harhata) may be dis- 

 tinguished from each other by the following points (cf. Fig. 1 in text): — 



E. norvegica, $ . The last thoracic segment on each side ending in a 

 blunt spine. The genital segment with genital swelling occupying the 

 lower part of the segment, the opening nearly round, guarded on each 

 side by a prominent blunt tubercle. Second foot : the external spine 

 of exopodite 2 does not reach the end of the first marginal spine of 

 exopodite 3, the second spine of exopodite 3 does not nearly reach the 



