Their absence from surface-layer samples, however, 

 indirectly fixes their upper depth limit, generally at 

 about 100 m. Spinocalanids have been collected in a 

 lesser number of deep closing-net samples taken at 

 discrete depths. A lower depth limit, if there is such a 

 limit, has not been fixed; some species have an ex- 

 traordinary vertical distribution, from 50 m to at least 

 5,000 m. The great vertical range gives these species a 

 potential for wide, in some cases worldwide, distribu- 

 tion in the relatively uniform and interconnected 

 deep-ocean water masses. The lack of records for some 

 species from entire oceans cannot yet be accepted as 

 an indication of real absence. In particular, the ap- 

 parent bipolar distribution of Spinocalanus antarc- 

 ticus should be reconsidered, to determine its dis- 

 tribution into lower latitudes. 



In the decades since World War II interest in the 

 Arctic Ocean has greatly increased, for commercial, 

 strategic, and scientific reasons. The heroic days of 

 the earliest Arctic explorations, when observations 

 were gained under the harshest conditions, are past. 

 In spite of the difficult and distant environment, in- 

 formation now accumulates relatively rapidly. The 

 development of air transportation and the use of 

 floating ice platforms have made all Arctic areas 

 accessible throughout the year. Still, most subjects of 

 investigation remain in an exploratory stage; this is 

 especially true of the oceanic plankton of the high 

 polar basins. The oceanic copepods, the most 

 numerous of the net-zooplankton, are the subject of 

 less than a dozen published reports, and only three or 

 four of these consider deepwater species. The present 

 study is based on collections of zooplankton from 

 Fletcher's Ice Island, in the Canadian Basin in 1967- 

 68. The spinocalanids from these collections are 



redescribed, and their vertical distributions are dis- 

 cussed. 



The systematics of the Spinocalanidae has been 

 reconsidered using characters in addition to those 

 usually considered, the antennae and legs. Many 

 named species are placed in synonymy, and two new 

 species are described. The family is now considered to 

 comprise 32 species, distributed as follows: 

 Spinocalanus (19), Monacilla (4), Mimocalanus (8), 

 and Teneriforma (1). Keys to all the species have been 

 prepared, with the goal of enabling an investigator to 

 identify even damaged specimens. 



Field Methods 



The sampling base for the Arctic collections was 

 Fletcher's Ice Island, also called "T-3." T-3 is a 

 tabular ice sheet ca. 8 X 13 km and 30 m thick, 

 fragmented from northern Ellesmere Island. T-3 is 

 caught up in the pack ice, with which it drifts at about 

 2-4 km/day. At the time the material to be described 

 was collected, T-3 was in the Canadian Basin, ranging 

 in latitude from 79°30'N to 85°N and in longitude 

 from 142°W to 175°W (Figs. 1, 2). Positions were 

 determined only every few days. Mohr (1959) and 

 Schindler (1968) have summarized the history and 

 use of the ice island. 



Zooplankton samples were collected through a hole 

 in the sea ice (3-4 m thick) bordering the island. A 

 small prefabricated plywood hut was assembled over 

 the hole; the hut housed a winch, with 4,000 m of 

 hydrographic wire, powered by a 5-hp gasoline engine. 

 The wire ran through a meter wheel attached to a 2-m 

 tripod placed over the hole; a 50-kg weight was 

 secured to the end of the wire. 



Figure 1. — Positions and track of Fletcher's 

 Ice Island ("T-3") in the Canadian Basin, 

 June-September 1967. 



