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In 1616 William Baffin, coasting up the icebound west coast of Greenland, reported: ‘The first of July we were come into an open sea, in the latitude of 75 degrees 40 minutes, which a new revived our hope of a passage…’ (Purchas 1625). From this point, at an unspecified longitude in the north part of Melville Bay, he cruised for 12 days in open water, up the Greenland coast to 77°30'N and down the west side of Baffin Bay to Bylot Island, seeing and naming on the way Smith, Jones, and Lancaster sounds. From Bylot Island south he found ‘a ledge of ice between the shoare and us’ as he continued past Pond Inlet and down the coast of Baffin Island. This is the first mention in written records, and the first known navigation, of an area that became well known two centuries later as the ‘North Water’.

The gross internal anatomy, food habits, local summer ecology and breeding c ycle of Them,isto libellula Mandt are studied in material from Baffin island coastal waters obtained in 1939 and 1940. The chitinous proventriculus projects backwards into the cavity of the midgut and forms a "gastric apparatus" which cuts off part of the wall of the anterior midgut from direct contact with the food. The gastric apparatus is strongly reminiscent of the peritrophic membrane in insects and the Onychophora. The food in the summer consists mainly of the smaller crustacean plankton; plant matter was also found in the gut. There is a high incidence of infection by a Gregarine parasite. The possible causes of the reduction in numbers of. Themhto in the fjord waters in August are discussed; the reduction is tentatively referred to the agency of the outflowing surface current coupled with the habit of Themisto o'f seeking the surface waters. The breeding cycle is of the alternating, or two-phase type which has been recorded by the writer in other arctic planktonic forms. There is a breeding period in the early part of the year and perhaps another in the autumn.J. Fish. Res. Bd. Can. Downloaded from www.nrcresearchpress.com by UNIV CALGARY on 10/02/12For personal use only.