CANADIAN FISHERIES EXPEDITION, 19U-15 



445 



definitely at the outermost stations (10 and IT). It decreased in abundance to the 

 north and to the west (perhaps also to the south). This perhai)s indicates that sur- 

 face boreal water was at tliat time cmninj;- around the southern side of the Newfound- 

 land hanks. 



This area was not explored during the second cruise. The distribution at that 

 time, as shown in fig. G, would indicate the presence of very little surface boreal water 

 south of the Newfoundland banks, probably owning to the pressing in of the surface 

 Gulf Stream water. The centre of abundance at this time was off the lower end of 

 Nova Scotia, where no stations were taken on the first cruise. Whether the animals 

 were transported to this point from the north during the intervening two months or 

 not must remain problematical, although the direction of the known surface currents 

 in these waters would support such a view. 



The rarity of S. serratodentata in north Kuropean waters as recorded by Ritter- 

 Zahony (1910, p. 2) and Apstein (1911, p. 174) is remarkable. It is rare even in the 

 open Atlantic off Ireland. Its occurrence on one occasion in the deep water of the 

 Skager-Rock, and only at a depth of 150 metres or more (Apstein) indicates a res- 

 trictdon to the deep salt water on the rare occasions when it is carried into the North 

 sea. 



(/) Sagitta bipunctata, Quoy et Gaimnrd. 

 1911. Ritter-Zahony, p. 10. 



" Acadia." 



This species was obtained only at the southernmost station of the second cruise 

 of the Acadia, at station 44 (fig. 1, horizontal dotted lines). It occurred in both sur- 

 face and open-net vertical hauls. It is a tropical surface form, but extends well north 

 in the Atlantic. Owing to its confusion with other species the records of its occur- 

 rence are untrustworthy. 



It was obtained l)y Bigelow in July- August, 1913, only in his more southern and 

 outer stations south of cape Cod. 



(.'/) Sagitta elegans Yorrill. Fig. 7. 



1911. Ritter-Zahony, p. 17 and figs. 1-3. 



This is the characteristic Sagitta of our Atlantic waters, from its general occur- 

 rence in the shallow water all along the coast. 



The range in size is from 2 to 52mm. iu length. Ritter-Zahony divides the species 

 into three subspecies, of which two, elegans and arctica, would be represented here. As 

 these are not distinct but are connected by intermediates, I have not thought it worth 

 while to consider them separately. The differences between the two are similar to the 

 differences between the two types of S. serratodentata- and are no doubt due to the same 

 cause, namely, difference in temperature during development. It is interesting to note 

 that the only place where individuals longer than 3Gmm. were found, was in the Bay 

 of Islands. In that place there is an extensive layer of water below the freezing point, 

 from about 50 fathoms to as much as 150 fathoms deep. Such an extreme condition 

 was not found elsewhere, and approaches the conditions in the Arctic regions. 



