PLANKTON OP THE GULF OF MAINE 335 



In the eastern Atlantic it is widely distributed in the North Sea (not, however, in 

 the Baltic, from which it is probably barred by low salinity), around Ireland, and in 

 the English Channel. It is also recorded from the Sargasso Sea and from off the 

 mouth of the Amazon (Apstein, 1900); but, as Huntsman (1921) points out, it 

 seems so unlikely that T. catharina should normally occur at these tropical stations 

 that the records call for confirmation. 



Slight differences have been described between the American and European 

 races of this worm (Huntsman, 1921), interesting because of a possible physiological 

 difference in their relation to the salinity of the water. 



T. catharina has been taken hero and there in the Gulf of Maine in every month 

 of the year, including midsummer (the warmest season), on the one hand, and late 

 winter and early spring (the coldest), on the other. As the chart (fig. 94) shows, it 

 is very generally distributed north of a line from Cape Cod to Cape Sable. For 

 example, it appeared at about 60 per cent of our stations in August, 1913; at about 

 50 per cent of the stations in the waters thus limited during February to May, 

 1920; at 5 stations (out of a possible 13) in the northern half of the gulf during 

 December and January, 1920-1921; and occasionally off Gloucester during the 

 winter of 1912-13. 78 



Thus, it is constantly present in the gulf throughout the year, with no definite fluc- 

 tuations in abundance from season to season except an apparent scarcity in late autumn 

 and early winter, evidence for which is our failure to find it at any of our stations in 

 the western part of the gulf in October and November, 1916, or in Massachusetts 

 Bay during November and December of 1912. We have also found it occupying 

 the same geographic range in the cold season as in the warm, which is also the case 

 around Ireland (Southern, 1911). 



Although Tomopteris is so large and conspicuous that one is not apt to overlook 

 it in the catch, it occurs so sparsely (usually from one to half a dozen individuals 

 per haul) that it may well have been missed by the net at other stations, though 

 actually present in the immediate neighborhood. 



As appears from the chart, T. catharina has been taken with about equal fre- 

 quency in the coastwise belt and over the deeper basin of the gulf. It is also 

 recorded (once only) from St. Andrews in Doctor McMurrich's plankton lists (p. 12) 

 and in the Bay of Fundy by Huntsman (1921), but we did not find it in Casco Bay 

 in July, 1912, when it was taken at several stations along the coast from Massachu- 

 setts Bay to Mount Desert (Bigelow, 1914, p. 121). As we have never taken 

 it in any harbor (e. g., Gloucester, Portland, Southwest, or Eastport, etc.) it is to 

 be looked upon as occurring chiefly outside the outer islands and headlands and 

 rarely in the estuarine waters tributary to the gulf. On the other hand, we have 

 never taken T. catharina anywhere on Georges Bank or Browns Bank at any season, 

 nor at any of our deep stations along the continental slope. Thus, while not 



» For records of T. catharina (as" T.hdgola-ndica") 1912 to 1913, see Bigelow, 1914 p. 121; 1914a. pp. 403-405; 1915, p. 301. Since 

 then it has been detected at the following stations: In 1914 at 10213, 10214, 10225, 10245, 10246, 10247, 10248, 10249, 10250, and 10255; 

 at stations 10267, 10270, 10290, and 10317 in 1915; 10398 in 1916; at stations 20048, 20050, 20052, 20055, 20056, 20057, 20059, 20060, 20062, 

 20079, 20080, 20081, 20084, 20085. 20087, 20092, 20093. 20096, 20097, 20098, 20100, 20107, 20113, 20114, 20115, 20116, 20119, 20125. 20126, and 

 20127 in the spring of 1920; and at stations 10489, 10490, 10494, 10495, 10499, 10510, and 10511 in the winter and early spring of 1920 

 and 1921. 



75898—26 22 



