PLANKTON OF THE GULF OF MAINE 119 



part of Georges Bank, and off Cape Cod (Bigelow, 1917, pp. 298 and 299). We 

 have not taken Limaeina on Browns Bank either in spring or in summer, but since 

 it has appeared at several of our stations over the shelf farther east, as well as on 

 German Bank, in June, July, and August, and in the eastern basin of the gulf in 

 March and April, it is more likely that our failure to find it on Browns Bank was 

 accidental than that this pteropod does not occur there. 



Our most productive summer catches of Limaeina retroversa have been as follows: 

 On July 29, 1912, we encountered a swarm of juveniles off Casco Bay (station 10019); 

 in 1913 great numbers were taken off Nantucket on June 21 (by Capt. John McFar- 

 land, lat. 40° 45' N., long. 70° W.); off Penobscot Bay, August 11 (station 10091); 

 and near Cape Elizabeth, August 15 (station 10104); while the largest haul of all, 

 yielding about 125 cubic centimeters of Limaeina (besides other plankton), was 

 made over the northeast edge of Georges Bank on July 20, 1914 (station 10215). 

 Thus, the few rich stations just mentioned (fig. 43) show no definite grouping in 

 any one part of the gidf, but are spread far and wide. We did not find Limaeina in 

 numbers at any time during the spring, summer, or autumn of 1915, though it was 

 taken at about 50 per cent of our stations for that year; nor was it more plentiful 

 in the gulf at our few stations for July and August of 1916, though odd specimens 

 were detected at about half of them. 



In spite of the erratic way in which Limaeina appears and disappears (or at 

 least vanishes from observation) in the Gulf of Maine, the records for the five years 

 1912 to 1916 show that in summer this pteropod is much less plentiful in the coastal 

 zone and out to the 100-meter contour, from Massachusetts Bay northward and 

 eastward as far as Mount Desert Island, than it is farther offshore. Limaeina has 

 appeared in less than 10 per cent of the June-August stations in this inshore zone, 

 to which w r e have paid particular attention, but seldom in any of the hauls at that 

 season in the inner part of Massachusetts Bay or in any of the other indentations of 

 the coast west of Mount Desert. Close proximity to the coast and shoalness of 

 the water do not necessarily imply a scarcity of Limaeina in summer, however, for 

 this, it seems, is its period of maximum abundance at St. Andrews, where Doctor 

 McMurrich found it at almost every station from mid-June until September in 1916. 

 Limaeina is likewise a regular summer inhabitant of the. coastal waters along the 

 outer shores of Cape Cod and of the shallows over German and Georges Banks, and 

 south of Nantucket. Furthermore, it may occasionally appear in great numbers in 

 Massachusetts Bay in summer, when it is usually rare or absent there, for Alexander 

 Agassiz (1866) found it swarming at Nahant (some 12 miles from Boston) during 

 the summer of 1863. 



A considerable number of records of Limaeina for September, October, and 

 November show that this pteropod, like Euthemisto, tends to work inshore in the 

 western side of the gulf in autumn. Thus, in 1915 00 it occurred at four out of six 

 late October and early November stations in Massachusetts Bay, whereas we have 

 only once found it inside a line from Cape Cod to Cape Ann in July or August of 

 recent years (station 10342, July 19, 1916). Similarly, no Limaeina were taken in 

 the hauls along the Maine coast inside the 100-meter contour in 1915 until Sep- 



*> See Bigelow, 1917, p. 299, for records of Limaeina in 1914 and 1915. 



