BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. 23 



various systematic zoologists who happened to be at the laboratory was constantly sought. 

 Specimens from each dredge haul of all species concerning which any doubt was believed 

 to be possible were brought back to the laboratory for further examination, and were 

 commonly bottled for reference to specialists. Some confusion of species probably 

 occurs in the records here presented, especially those derived from the earliest dredging 

 work; but we believe these cases to be few, and we have endeavored to indicate such 

 possibilities in their proper place in the records. Moreover, the supplementary dredging 

 trips to be mentioned below have removed many of these ambiguities. 



Cases of omission are doubtless present in great frequency, and many of them would 

 have been inevitable under the most favorable circumstances. Microscopic organisms 

 were entirely overlooked. The Foraminifera were collected and listed during only one 

 of the seasons in which the original "stations" were dredged. The smallest Crus- 

 tacea and worms, and in fact minute organisms in general, were undoubtedly over- 

 looked in very large measure. Certain forms were regularly neglected during the earlier 

 portions of the work, but were later sought for and preserved, after our attention had 

 been called to them by special students of the organisms in question. This was particu- 

 larly true of some of the more minute hydroids, Bryozoa, amphipods, and Annulata. 

 The charts representing the distribution of such forms would consequently be misleading 

 unless this fact were taken into consideration. The apparent absence of a species through- 

 out a wide area would not in such cases imply its actual absence. But here again we 

 have indicated such possibilities in the discussions of the various groups. In a large 

 proportion of cases an example of a doubtful species was preserved from each station 

 at which it occurred. Sometimes, however, a single specimen was chosen as representa- 

 tive of a considerable number of stations. This proved to be a dangerous practice. 

 It has sometimes happened (most often, perhaps, in the case of encrusting Bryozoa and 

 of certain small mollusks) that the representative sample proved to comprise two or more 

 species. The identity of the species which had been taken at the other stations was, of 

 course, rendered uncertain. Such ambiguities are duly noted in the records, as also 

 other possible sources of error and confusion. 



Again, certain misleading results have arisen from the differences in the dredges 

 employed at various points. So far as these relate to the character of the bottom they 

 will be discussed under that head. It need only be pointed out here that the beam 

 trawl alone would bring up no bottom sample except occasional stones, and would thus 

 miss most of the organisms except the larger algae and such animals as crawl upon the 

 bottom or at least project considerably above its surface. On the other hand, the scrape 

 dredge alone, on account of its small aperture, would commonly miss the fishes and 

 other actively swimming organisms, and, indeed, would have a much smaller chance 

 of gathering in any of the forms which dwell freely on the bottom. The burrowing 

 species, however, or such, at least, as do not burrow deeply, would commonly be cap- 

 tured. At the majority of the Fish Hawk stations, as already stated, the two were 

 used together or in succession. 



During the earlier part of the work the bottom material (sand, gravel, shells, etc.) 

 was not searched with sufficient care, and considerable numbers of species were doubtless 

 overlooked for this reason. Later more careful methods were adopted, such as have 

 alreadv been described. 



