CANADIAN FISHERIES EXPEDITIOS, IDUflo 427 



Vertical. — This species was obtained only in deep open-net hauls down to 2'00 metres 

 or more, and in one closing-net haul below 250 metres. It was therefore distributed from 

 above 200 metres to below 250 metres. All the hauls from 90 metres up, and shallower, 

 were negative. Michael (1913, p. 31) found it very rarely above 25 fathoms, and 

 attaining its maximum abundance below 250 fathoms. He does not, however, distin- 

 guish S. maxima from this species. Ritter-Zahony (1911, p. 14) gives its distribu- 

 tion as from 100-200 metres downwards. It is thus typically in the deeper layers of 

 water. 



Horizontal. — This species is cosmopolitan and extends well to the north in the Atlantic. 

 It is oceanic, being confined to deep water. In our waters its distribution is very similar 

 to that of S. hexaptera, it was found only in the outer stations. But it occurred in 

 more of these than did hexaptera, pressing farther in towards the continental shelf. 

 In the May- June cruise it was found at the same stations as hexaptera, and did not 

 occur at Acadia station 14, where a suitable haul was made. It would seem to have 

 been at that time about sixty miles oif the continental shelf, but the data are quite 

 insufficient. In the July-August cruise (its distribution is shown by the vertical 

 continuous lines in fig. 1) it was found in moderate abundance (about half-a-dozen 

 specimens) at the outermost stations (44, 56, 74, 75) with hexaptera, and as well in 

 some of the neighbouring stations (42, 55, 70), but only one or two si^ecimens in each 

 case. Thus it virtually came to the edge of the continental shelf. It might have been 

 expected at stations 45, 72 and 76. Station 45 was peculiar in giving only one Chaetog- 

 nath, S. serratodentata. Stations 72 and 76 appear to have had too great an amount 

 of coastal water (witness the presence of »S'. elegans). It is perhaps worthy of note that 

 at only one station (Acadia 16) were S. lyra and S. elegans found together, and at only 

 four stations were they both absent. The inner limit in distribution of S. lyra almost 

 corresponds with the outer limit of S. elegans. Although coming very close in, Sagitta 

 lyra does not appear to be carried over the banlvs or up the gullies between the banks 

 or up into the gulf of St. Lawrence. 



It belongs to the deeper part of the bank of Gulf Stream water, and is carried in 

 small numbers into the " cold wall " of boreal water that Hjort (1912, p. 10) has shown 

 to exist along the southern side of the Grand Banks between the Gulf Stream and the 

 continental shelf, and that Bigelow (1915) has shown to become narrower as we pass 

 southward along the coast. "We may take arbitrarily a salinity of 35 per thousand as 

 forming the boundary line between the two. It is present in this boreal water only 

 south of the angle where the Gulf Stream is deflected to the south by proximity to the 

 Grand Banks, as if some mixing of the two waters occurred there. 



The passage of this species from the Gulf Stream into the boreal oceanic water, 

 and the failure of 8. hexaptera to pass in a similar direction is perhaps to be explained 

 by the fact that S. lyra occurs in deeper, colder water than S. hexaptera, and is there- 

 fore more apt to pass through the bottom of the Giilf Stream. The rarity of S. hex- 

 aptera may also be responsible for our failure to get it in the boreal oceanic water. 



Dr. Bigelow (1915, p. 297) lists S. lyra from each of his four stations taken just 

 outside the continental shelf south of cape Cod in July-August, 1913, and not from 

 those inside, except for two specimens from the gulf of Maine. 



