BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. 133 
With the exception of those four species comprised in the last two lists, the amphi- 
pods, when recorded from Buzzards Bay at all, were nearly always taken in the vicinity 
of land, i. e., at the adlittoral stations. In a large proportion of cases the Bay stations 
were near the passages connecting with Vineyard Sound, or close to the lower end of 
the Bay.® 
On the other hand, even within the Sound, certain species are found not to have 
an unrestricted distribution. For example, Hawustorius arenarius, Byblis serrata, 
Calliopius leviusculus, Pontogenva inermis, and Jassa marmorata are in large degree 
restricted to the western half of the Sound, while Lysianopsis alba, Batea secunda, and 
Autonoé smitht are for the most part restricted to the eastern half. One of the two 
predominantly Bay-dwelling species (Ampelisca macrocephala) and perhaps also the 
other (Ptilocheirus pinguis) appear to be in some measure restricted in the Sound to 
points where the bottom is muddy. The difference between the Bay and the Sound 
in respect to tneir amphipod faunas, and in considerable measure the local distribution 
within each of these bodies of water, are for the most part explainable by reference 
to the character of the bottom. Just such types of distribution have already been 
encountered in the case of other groups and need not be discussed here. Certain cases 
which appear to be explainable by reference to temperature will be considered shortly. 
An interesting feature respecting the amphipod life of the Bay and the Sound 
appears when we consider the average number of species taken per dredge haul for 
each body of water and for each vessel. The figures are as follows: 
Vineyard Sound: 
LOvisiolal 6 Urly7) limi (ies ma te Ne 34) eS he oe ee Lt SoA ade 1.8 
HEIGTOPIE LNG RAG eine Comat ee mT RAL, LLL RL Oe Rs ee 1.9 
Buzzards Bay: 
ESA EMER NV IC Aa ete it at als a. NN tet es hs ois 0. seis Byaiaslnys VN ead eae Es 13/4 
Padlarope, js5er elsseheieiestaees .foretya’. 20. 2s. JU Rae ee tere 
While these figures were considerably higher for the Sound stations than forthe 
Bay stations, there is nothing like the disproportion which might have been expected 
in view of the fact that the number of predominantly Sound-dwelling species which 
were shown upon our charts was so much in excess of (7% times) the number of 
predominantly Bay-dwelling species. 
Again, the average number of species per dredge haul is the same (1.6) for each of 
the three types of bottom distinguished. And when we consider the lists of ‘‘preva- 
lent’’ species for the various groups of stations, we find that only such one (Unciola 
trvorata) occurred at one-fourth of the Vineyard Sound stations of the Fish Hawk, 
while three species (Pitlocheirus pinguis, Unciola irrorata, and Ampelisca macrocephala) 
occurred at an equal proportion of Buzzards Bay stations. This condition seems to be 
only explainable on the supposition that while the number of species which inhabit 
Vineyard Sound is greatly in excess of the number found in Buzzards Bay, such 
species as do occur in the latter are of much more general prevalence throughout its 
extent. A discussion of similar phenomena has already been given in chapter II. 
Two apparent cases of distribution in relation to temperature are Calliopius levius- 
culus and Pontogenia inermis, which occur, so far as our dredging records show, primarily 
«In some cases, just without. Here and elsewhere stations have been classed as Bay or Sound stations which lay on the Bay 
or Sound sides, respectively, of Sow and Pigs Reef, extending from the end of Cuttyhunk Island. 
