32 BULLETIN OF THE BUREAU OF FISHERIES 



indeed, in all locations where conditions may be described as estuarine — and dominate 

 for a mile or two out from the coast line generally. No detailed study of the plank- 

 ton of any such situation tributary to the Gulf of Maine has yet appeared, but 

 Willey's (1913 and 1915) and McMurrich's (1917) observations at St. Andrews, 

 with the lists contributed by Doctor McMurrich (p. 12) and the record that might 

 be collected from many sources of the abundance of various medusae and of larval 

 forms of many kinds inshore, show that the gulf is no exception to the general rule. 



The complexion of the plankton at Woods Hole recently described by Fish 

 (1925) may serve as an indication of the preponderance of neritic forms that may 

 be expected in the Gulf of Maine bays and harbors and close along its coast line 

 generally. Thus, Fish classifies 42 of the characteristic diatoms as neritic and 

 only 16 as oceanic, while at least 13 out of 15 hydromedusae described by him as 

 " occurring commonly in surface towings" (Fish, 1925, fig. 26) are characteristic of the 

 neritic group and only one oceanic. Two neritic scyphomedusae occur in abundance. 

 Only two of the many annelids listed from his tows (Sagitta and Tomopteris) are 

 truly pelagic when adult, for the others swim only during the breeding season or as 

 larvae. 



Molluscan larvae are at times abundant in the Woods Hole plankton. The 

 neritic phyllopods Evadne and Podon are characteristic of the local tows, as are 

 the larvae and sometimes the adults of neritic mysids. Fish found barnacle larvae 

 abundant in their season, bottom-dwelling amphipods were taken in large numbers 

 in the tow during their breeding season, and the larvae of decapod Crustacea — 

 shrimps, prawns, crabs, and hermit crabs — are dominant. On the other hand, 

 no euphausiid is a permanent member of the local plankton, though several species 

 have been recorded at Woods Hole. Thus, aside from the copepods, the oceanic 

 element of the Woods Hole plankton is wholly overshadowed by the neritic. 



If one were to turn to the Gulf of Maine de novo, one might naturally expect 

 the plankton of its central portion to be so largely recruited from the coastal zone 

 that neritic elements would loom large there also, judging from the form, length, 

 and complexity of the shore line with the abundant and varied bottom fauna which 

 it supports; from the confinement of the gulf by the extensive and shallow offshore 

 banks on the ocean side; from the great volume of river water that pours into it; and 

 from the fact that the tides are strong enough in places to stir the water thoroughly. 

 Our first summer's cruise (in 1912) was enough to show that this is not the case 

 but that the pelagic communities of the gulf a few miles out to sea are predominantly 

 oceanic, except over the offshore banks. 



Our subsequent cruises have corroborated this for summer, autumn, and winter 

 for all the years of record, and for the whole offshore basin of the gulf, where we 

 have never found neritic forms, plant or animal, playing a role of any importance 

 in the plankton except for a brief period in spring, as pointed out below. 



The rarity of animals of coastwise origin or affinity in the open gulf in summer 

 (except within a trivial distance of land and over the shallow banks) will appear 

 from the following facts of distribution, already summarized in an earlier report 

 (Bigelow, 1917, p. 251). 



