BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. Lis 
ture, is probably responsible for the greater prevalence of this species in the western 
half of Vineyard Sound, where, as we have pointed out elsewhere, certain typical sand- 
dwelling species find their most congenial habitat. 
On the other hand, certain less frequent species (not among those charted) were 
dredged chiefly upon muddy bottoms. Particularly worthy of mention is the holo- 
thurian Caudina arenata, which was taken by us seven times in Buzzards Bay and only 
once in Vineyard Sound. 
The part played by temperature in determining distribution is rather strikingly 
illustrated by some members of our echinoderm fauna. The local distribution of the 
two commoner species of Asterzas is quite in keeping with what we know of the ranges 
of these two forms upon our coast. A glance at charts 48 and 49 shows us that whereas 
Asterias forbest has a practically unrestricted distribution in local waters, A. vulgaris, 
on the contrary, is most prevalent in the colder portion of Vineyard Sound. Indeed, 
there is seen to be a progressive concentration of the distribution symbols as we pass 
from the eastern to the western end of the Sound, while in the Bay the records are con- 
fined to the neighborhood of the open ocean. It is likewise worth noting in this con- 
nection that the latter species was recorded from all seven of our regular dredging 
stations at Crab Ledge, while Asterias jorbest was recorded but once. 
As stated by Clark, the range of the latter species upon our coast is from ‘‘ Maine to 
the Gulf of Mexico,” but it is said to be “‘rare or local north of Cape Ann.” It is pri- 
marily a shallow water form, which does not appear to pass beyond depths of 25 or 30 
fathoms. A. vulgaris, on the other hand, ranges from Labrador to Cape Hatteras, 
though it is ‘“‘rarely seen in shallow water * * * south of the Woods Hole region.”’ 
It is recorded from depths as great as 358 fathoms. 
Such natural expectations as to distribution in local waters are not, however, 
realized in the case of another starfish, Henricia sanguinolenta. This species, also, is 
listed as “‘littoral only as far south as the Woods Hole region,” while, to the northward, 
it extends to Greenland. The dredging records show it to be abundant throughout 
the length of Vineyard Sound and, indeed, to be rather commoner in the eastern 
(warmer) half. It is likewise recorded from scattered stations in Buzzards Bay, even 
well toward its head. For this species, then, temperature seems to be a minor factor in 
determining the distribution in local waters. 
Of considerable interest are the relative distributions of our two local sea urchins, 
Arbacia punctulata and Strongylocentrotus droebachiensis. The former species appears 
to be of general occurrence throughout Vineyard Sound, except for the portion adjoining 
the open ocean. In Buzzards Bay it occurs as far as the upper end, but it seems here 
to be restricted largely to the vicinity of land. Strongylocentrotus, on the other hand, 
occurs in greatest abundance in the western portion of Vineyard Sound, though occa- 
sional specimens have been taken as far eastward as West Chop. In Buzzards Bay it 
is found only near the extreme lower end. Again, Strongylocentrotus was taken at all 
seven of the stations at Crab Ledge, while Arbacia was not found there once. The 
latter species occurs locally at all depths, even up to the low-water mark. The former 
species, on the other hand, is rarely if ever taken at such slight depths, except in 
northern waters.2 We have very few records of its occurrence in less than 5 fathoms, 
@ Verrill, it is true, states that this species occurs ‘‘at low water on the outer rocky shores." This can not bea common occur- 
rence locally, however. 
16269°—Bull. 31, pt r—138 
