332 BULLETIN OF THE BUREAU OF FISHERIES 



represented in the tow by occasional examples only, even though the water be well 

 over 100 meters deep. Its apparent rarity in the southeastern deep of the gulf — I 

 say apparent because we have made few tows there — is interesting in connection 

 with the probable route which it follows in its journeyings (p. 64). Eukrohnia 

 occasionally reaches the trough between the Isles of Shoals and Jeffreys Ledge, 

 where we have found it at one station (20093, April 9, 1920); but apparently it 

 never finds its way into the sink at the mouth of Massachusetts Bay, or at least so 

 rarely that we have never taken it there, though we have towed repeatedly at 

 various seasons of the year 75 . 



The largest catch of Eukrohnia actually counted so far from any one of our tow- 

 net hauls has been 63 specimens (station 10093, haul from 85-0 fathoms, August 12, 

 1913). Possibly other hauls may have yielded more, but, if so, very rarely. We 

 have no reason to suppose that it ever occurs anywhere in the gulf in numbers to 

 compare with S. elegans or even with .S. serratodentata. 



A catch of 20 to 50 individuals in half an hour's towing (which may be stated as 

 a fair average of the more prolific horizontal hauls, whether made with the 1-meter 

 open net or with the slightly smaller closing net) means a very sparse population, 

 indeed, when translated into terms of actual density of aggregation in the water — 

 say one Eukrohnia to every 30 to 70 cubic meters of sea water. To make this more 

 graphic let us say not more than one Eukrohnia in a space the size of an ordinary 

 room. 



There is no direct evidence that Eukrohnia breeds within the gulf at any time 

 of year, sexually mature specimens never having been found there. Hence the local 

 stock is maintained chiefly if not entirely by immigration from centers of production 

 elsewhere, but a few large Eukrohnia (up to about 45 millimeters in length) with 

 well-developed ovaries were taken among the more numerous immature specimens 

 in the deep haul over the slope abreast of Cape Sable on March 19, 1920 (station 

 20077). 



Eukrohnia is never absent from the gulf at any time of year, but our records, 

 if they can be taken at face value, point to the late spring and early summer as a 

 period of decided scarcity, for only one specimen was taken at our May stations in 

 1920 (station 20125), and none at all during May or June in 1915. 



The stock of Eukrohnia present in the Gulf of Maine fluctuates unmistakably 

 and widely from year to year. The summer of 1913, when it occurred in all but one 

 of the horizontal hauls deeper than 100 meters and at a total of 10 stations in July 

 and August, was the best summer for it in our experience, while the summers of 1912 n 

 and 1915 stand at the other extreme. In March and April, 1920, Eukrohnia was 

 detected in 60 per cent of all the horizontal hauls deeper than 100 meters, and at 

 21 stations scattered far and wide over the gulf; likewise in the deep water along 

 the continental slope. 



" For records of Eukrohnia, 1912 to 1916, see Bigelow, 1914, p. 123; 1915, p. 294; 1917, p. 298; and 1922 pp. 138 and 155. During 

 the spring of 1920 it was recognized at stations 20044, 20053, 20055, 20057 20064 20068 20069 ,20074 20075. 20077, 20079, 20080, 20081 

 20086, 20087, 20088, 20093 20097, 20098, 20107, 20112, 20113, 20114, 20116, and 20125, and during the winter of 1920-1921 at stations 10490, 

 10494, 10496, 10497, and 10499. 



' • Found only once in 1912 (Bigelow, 1914, p. 123), three times within the gulf, in July and August, 1915, once on Browns Bank 

 and once over the continental slope abreast of Shelburne, Nova Scotia (Bigelow, 1917, p. 298). 



