I. '21. 11 



meet at the tip. They are formed of two joints, the basal 

 one short, thick, and dilated proximally. The distal joint 

 is longer and is expanded into a broad leaf-like structure, the 

 edges of which are curled inwards and Hned with stiff bristles. 



These appendages are absent in the female. 



On the second abdominal segment in the male there is a 

 pair of pleopods which are uniramous like the first pair, but 

 are larger and broader, and more widely separated at the 

 base. The basal joint is stout, uniform in thickness, and bears 

 a group of long setae. The second joint is slightly twisted 

 near its tip and its edges are curled, so that it is concave 

 inwards. The edges are furnished with a number of stiff 

 setae. 



Behind these there are, on the left, three unpaired pleopods. 

 They are biramous, but very unequally so, one of the branches 

 being almost vestigial. 



In the female there are no paired pleopods. On the left 

 side there are biramous pleopods on the second, third, fourth, 

 and fifth abdominal segments. In the first three the two 

 branches are almost equal, while in the fourth the posterior 

 branch is very minute. These pleopods are much longer 

 and broader than the same appendages in the male. 



The uropods are of the usual hook-like structure. 



Size : — The carapace usually measures about 25 mm. 



General Distribution. — This species affords one of the best 

 known examples of the cosmopolitan distribution of deep-sea 

 organisms. It has been found as far north as Iceland (Hansen), 

 and as far south as Tristan d'Acunha (Henderson). At suit- 

 able depths it extends round the globe in temperate and 

 tropical waters. It has been recorded from the following 

 localities : --West of Ireland (Pocock), Faeroes and Iceland 

 (Hansen), off Nova Scotia (Smith), East Coast of the United 

 States (Smith), West Indies (Smith), Sargasso Sea, Bermuda 

 (Henderson), Atlantic coast of South America, Pacific coast 

 of South America (Henderson), Galapagos and Gulf of Cali- 

 fornia (Faxon), off Yokohama (Henderson), Papua and 

 Philippines (Henderson), Bay of Bengal, off Cape Comorin, 

 Arabian Sea (Alcock), East and South coasts of Africa (Balss), 

 Tristan d'Acunha (Henderson), Sierra Leone (Milne-Edwards 

 and Bouvier), off West coast of Sudan and Morocco, at the 

 Azores and Canaries and off Spain and Portugal and in the 

 Bay of Biscay (Milne-Edwards and Bouvier). 



Vertical Distribution. — The species inhabits all the great 

 ocean depths. The greatest recorded depth is 2,260 fathoms 

 in the Atlantic. It has also been taken in the comparatively 

 slight depths of 400 fathoms and 500 fathoms, and once even 

 in 250 fathoms (Smith). Hansen records specimens taken in 

 590 fathoms, and 442 fathoms, Milne-Edwards and Bouvier in 

 2,224 fathoms, 1,736 fathoms, 509 fathoms ; Alcock in 1,997- 

 705 fathoms. 



