the transition zone in the North Pacific and is not 

 reported from anywhere else. Previous studies on 

 the distribution of all seven species of 

 Nematoscelis in the Pacific Ocean are sum- 

 marized by Brinton (1962). 



Only four species of Nematoscelis have been 

 reported from the Atlantic Ocean. Moore (1952) 

 studied ocean-wide distributions of many 

 euphausiids in the North Atlantic Ocean, includ- 

 ing N. microps and A^. megalops. Einarsson (1945) 

 also reported TV. megalops from the northeastern 

 Atlantic. From the Mediterranean Sea N. 

 megalops, N. microps, and N. atlantica were re- 

 ported by Ruud (1936) and Casanova-Soulier 

 (1968). Incorporating all previous records Mauch- 

 line and Fisher ( 1969) have provided a generalized 

 picture of the distribution of Nematoscelis in the 

 Atlantic Ocean. Gopalakrishnan (1973) examined 

 the pattern of vertical distribution of 

 Nematoscelis species of the Pacific Ocean. 



FISHERY BULLETIN: VOL. 72. NO. 4 



METHODS AND MATERIALS 



The Indian Ocean portion of the present study of 

 Nematoscelis is based on samples collected during 

 the IIOE. This expedition was a collaborative ven- 

 ture in which 10 countries participated and 16 

 vessels collected zooplankton samples as part of 

 the biological program during 1960-65. The com- 

 posite pattern of stations occupied during 70 

 cruises provided coverage of most geographical 

 provinces of the Indian Ocean (Figure la, b). A 

 standard procedure was followed by all participat- 

 ing vessels for collecting zooplankton samples. 

 Accordingly, each sample was obtained by using 

 the Indian Ocean Standard Net (lOSN) which was 

 specially devised for the IIOE (Currie, 1963). It is a 

 ring net with a mouth area of 1 m^ and a length of 

 5 m. The straining surface is nylon gauze of 

 0.33-mm mesh. Hauls were as nearly vertical as 

 possible, from approximately 200-m depth to the 



20» io» «• w w 70- ac so- IOC no- i20* ixr i4o- iso* 



Figure 1. — Plankton samples examined for Nematoscelis of the Indian Ocean; a - SW Monsoon period. 



1040 



