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 Limacina 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 Limacina 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 Limacina (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 gulf, but are spread far and wide. We did not find Limacina 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 Limacina 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. Limacina has 
appeared in less than 10 per cent of the June-August stations in this inshore zone, 
to which we 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 Limacina 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. 
Limacina 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 1S63. 
A considerable number of records of Limacina 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 60 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 Limacina were taken in 
the hauls along the Maine coast inside the 100-meter contour in 1915 until Sep- 
t0 See Bigelow, 1917, p. 299, for records of Limacine in 1914 and 1915. 
