BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. 143 



degree this is due to the small number actually present in our local waters and to what 

 degree it is due to an insufficient search can not be stated. 



The ranges of our two commoner species, as stated by Wilson, are: 



Tanystylum orbiculare From off Marthas Vineyard to Virginia. 



Anoplodactylus lentus Long Island Sound; Woods Hole; Eastport, Me. (i record). "■ 



Thus the former appears to be a predominantly southern form, while for the latter 

 the data are insufficient to warrant us in assigning to it a range. 



One pycnogonid, which was taken upon the gulf weed on a number of occasions, 

 is Endeis spinosus Montagu. This, like the gulfweed fauna in general, is doubtless an 

 exotic species which comes to us from southern waters. Its presence on the weed is 

 rather unexpected, considering the ordinary habitat of this species in European waters. 



XI. INSECTA AND ARACHNIDA. 



There are, of course, very few strictly marine insects in existence, and it is doubt- 

 ful whether any of our local species can be so regarded. The thysanuran species 

 Anurida mariiima is, however, perhaps as nearly marine as are certain of our littoral 

 Crustacea. Verrill and Smith record having taken in the vicinity of Woods Hole a 

 number of insect larvje, which appear to have been living in sea water. One of these was 

 described by Packard as a new species. Most of the insects listed in that report were, 

 however, beach-dwelling species, which seldom or never enter the water. 



The list prepared by the writers comprises for the greater part species taken in 

 brackish ponds in the neighborhood. Many of these were larvae, and about half of 

 them have not been determined specifically. In many, if not most, cases these insects 

 are ones which are known to dwell in fresh-water ponds as well as brackish ones. It 

 has been thought worth while to include them here, however, since no list has ever 

 been published of our local brackish-water insects. 



The single arachnid here listed {Chcrnes oblongus) is scarcely to be regarded as 

 marine, though it has been taken under stones along shore, near low-water mark. 



9. MOLLUSCA. 



MoUusks, or their shells, have commonly constituted by far the most conspicuous 

 feature of the organic contents of the dredge. In respect to the number of species 

 likewise, the mollusks have generally preponderated, there frequently being more rep- 

 resentatives of this group contained in a given dredge haul than of all the other phyla 

 combined. Likewise the total number of molluscan species recorded in the course of 

 our dredging operations is considerably greater than that of even the Crustacea, though 

 the latter group preponderates as regards the number recorded for the region as a whole. 

 It must be stated, however, that the vast majority of specimens taken were merely 

 dead shells, and that many species were rarely or never taken in a living condition. 

 This preponderance of molluscan remains in our dredging records is obviously due to the 

 enduring character of the exoskeleton of these animals, which insures the accumulation 

 of shells, even in the case of the less common species. Another fact which results 

 directly from the one just mentioned is the relatively great frequency with which most 

 of the molluscan species were dredged. Of the 127 species which appear in our dredg- 

 ing records, 68, or more than half, are recorded from more than 10 stations each, while 



a This is to be regarded as a doubtful record. 



