PLANKTON OF THE GULF OF MAINE 315 



Massachusetts Bay region. Here we found it constituting from one-fourth to one- 

 half of the rather scanty tow in January, 1913, and it dominated the planktonic 

 community off Gloucester on February 13. 



Sagitta elegans certainly is endemic in the Gulf of Maine. Huntsman and 

 Eeid (1921, p. 104), to whom we owe (la- only local record of its eggs (this for the 

 Bay of Fundy), found from examination of ovarian eggs that in the Bay of Fundy 

 the ''spawning season is a long one, extending from the end of March or the begin- 

 ning of April to September at least. September 4 would seem to be near the end 

 of the season." Corresponding to this, they found eggs (identified by comparison 

 with large series of eggs and young Sagitta?, from the southern part of the Gulf of 

 St. Lawrence, an important breeding ground) in the Bay of Fundy plankton from 

 April to October, numerous or rare locally according to the abundance of the adult 

 Sagitta?. Huntsman and Reid further point out that the proportional abundance of 

 eggs at different stages in development proves that they do not develop properly in 

 the Bay of Fundy until September, the warmest month of the season, nor did they 

 find the young Sagitta?. in any numbers in the plankton until that time. However, 

 the young proved to be even more widely distributed than their parents, occurring 

 not only in the open bay but also up the estuaries, where the adults arc not to be 

 found : and in general the younger stages were most plentiful at locations where the 

 water was stratified vertically as to its temperature and density, and least so where 

 vertical circulation was most active. 



Huntsman and Reid concluded (and I believe justly) that the Bay of Fundy is 

 such an unfavorable environment for the reproduction of S. elegans that the stock 

 raised there locally is small and that the Sagitta population is kept up by immigra- 

 tion from the Gulf of Maine. 



Sagitta eggs have not been detected (perhaps because not especially sought) 

 in our plankton hauls in the open gulf, nor has the probable spawning season, as 

 revealed by the state of the ovarian eggs, yet been established except for the Bay 

 of Fundy, a region so pecidiar in its hydrography as to be a law unto itself. Statisti- 

 cal study of the relative sizes of the Sagittae captured in our hauls, from wmich much 

 information about the seasons and localities of reproduction may be hoped, is like- 

 wise a task for the future. However, I may point out that catches of S. elegans 

 made prior to mid-May during the springs of 1915 and 1920 consisted chiefly of 

 very large individuals, such as might be expected toward the end of a period of growth. 

 In 1915 it was not until June 14 that Sagittae less than 10 millimeters in length were 

 recognized among the plankton of the gulf. In 1920, however, equally young 

 S. elegans (8 millimeters long) were taken in Massachusetts Bay as early as May 16 

 (station 20123), with still smaller stages (5 to 12 millimeters long) on the western 

 part of Georges Bank on the 17th (station 20128), and from June on through the 

 summer, until the last of October, specimens smaller than 10 millimeters have been 

 detected at a considerable proportion of our stations. 68 



On the whole, then, it is safe to say that S. elegans is a late spring and summer 

 breeder in the Gulf of Maine, in so far as any considerable production is concerned, 

 but probably it reproduces more or less throughout the entire year. Fish's (1925) 



" Oct. 31, 1916, is our latest date for specimens oi 10 millimeters or shorter (station 10399). 



