BIGELOW: COAST WATER EXPLORATION OF 1913. 
299 
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The most important feature of the collection, from the geographic 
standpoint, is the presence of a very characteristic tropical fauna, 2. ¢., 
Sagitta enflata, S. hexaptera, S. bipunctata, small S. serratodentata, 
and Pterosagitta draco in the coast water south of Delaware Bay and 
in the inner edge of the Gulf Stream. This is just what was to be 
expected from hydrography, and agrees with the tropical aspect of the 
plankton as a whole in those regions. 
Elsewhere in the Grampus collecting ground the chaetognath fauna 
is typically boreal, characterized by the presence of Sagitta elegans 
| in abundance, and of large specimens of S. serratodentata. Though 
Sagittae were taken at nearly all our Stations, it was only at 
| eight (10057, 10059, 10060, 10061, 10070, 10103, 10105) that they 
Were an important constituent of the plankton, quantitatively 
speaking. 
Sagitta elegans was the prevalent Sagitta in the Gulf of Maine, 
where it was found at all Stations, three times in swarms (10057, 10103 
10105). It likewise swarmed on George’s Bank early in July (Station 
10059); and was the most abundant species over the continental shelf 
east of Long Island. But it was rare in the coast water further 
\west and south, and lacking outside the continental slope, as well as 
over the shelf south of Delaware Bay. And this agrees with its 
boreal habitat on the other side of the Atlantic. It was usually most 
abundant at about twenty fathoms depth; being numerous on the 
surface on one occasion only. 
| Sagitta serratodentata was likewise taken in the Gulf of Maine; but 
at eight stations only, and always in small numbers. And it was less 
qumerous than elegans over the shelf south of Marthas Vineyard. 
But it was the prevalent Sagitta in the shallow waters south of New 
| 
