98 BULLETIN OF THE BUREAU OE FISHERIES. 



These charts nearly all agree in showing the paucity of coelenterate life in Buzzards 

 Bay, to which reference has already been made. In fact, but two species (Eudendrium 

 ramosum and Astrangia dance) appear to be of anything like as general occurrence in 

 the Bay as in the Sound. Two species among those charted were not recorded from a 

 single station in the former body of water, while some of the others are confined within 

 its limits to the extreme lower end or to the immediate neighborhood of land. This 

 last condition is found to obtain in the case of many species belonging to nearly every 

 group which do not thrive upon muddy bottoms, and their distribution is readily 

 explainable by reference to this fact. Hydroids, as is well known, depend for support 

 upon a solid substratum, such as is afforded by stones or dead shells, and their frequent 

 occurrence upon bottoms which are listed as of pure sand is doubtless made possible 

 by the presence of shells. Where such solid objects occur in the Bay, however, they 

 are commonly more or less covered by soft mud. Nevertheless, at least one species of 

 hydroid, Eudendrium ramosum, has established itself in considerable abundance on 

 the floor of Buzzards Bay, a fact which is difficult to explain when we consider the 

 almost total absence there of Pennaria tiarella, a species having a quite similar mode of 

 life, and one which is abundant throughout the Sound. 



Of considerable interest is the scarcity of Hydractinia echinata over the whole central 

 area of Buzzards Bay. That this is not due to the scarcity within this area of the her- 

 mit crabs upon whose shells Hydractinia commonly dwells may be seen by reference to 

 charts 109, in and 112, from which it is evident that the three commonest local Paguri 

 are present throughout the entire Bay. It was at first thought possible that the non- 

 appearance of this hydroid in the records of the Fish Hawk for Buzzards Bay might 

 have been due to the failure of those responsible for the latter series of stations to 

 include it when listing the contents of the dredge. That this is not a satisfactory expla- 

 nation was shown in the course of some supplementary dredgings made during the 

 summer of 1909. Hermit crabs (P. longicarpus and P. annulipes) were taken at 16 of 

 the former Fish Hawk stations, but in only a single instance was Hydractinia met 

 with, though Podocoryne was noted three times." 



Several of the hydroids, particularly Tubidaria couthouyi and Thuiaria argentea, 

 appear to show a marked preference for the eastern half of Vineyard Sound, where the 

 bottom is in large measure stony. The distribution of Obelia geniculata is probably 

 dependent upon that of certain algae, to which it is generally found attached. Its 

 abundance in the vicinity of Gay Head probably stands in direct relation to the occur- 

 rence there of large numbers of the kelps (Laminaria) , upon which it frequently grows. 



At least two very instructive cases are to be noted among the species charted, 

 which appear to be intelligible only by reference to temperature conditions. We refer 

 to the two actinians, Alcyonium carneum and Astrangia dance. The former was found 

 to be confined to the western end of Vineyard Sound and the extreme lower end of 

 Buzzards Bay. It was not surprising, therefore, to meet with this species at several 

 of the Crab Ledge stations. The case is quite comparable with that of the sponge, 

 Polymastia robusta, referred to on page 94, and with many others which will be considered 

 later. The limits of distribution for this species, so far as known, are: Rhode Island 



o These supplementary dredgings, however, added several species to the fauna of the Bay, so far as recorded by us. These 

 were Clytia cylindrica, Pennaria tiarella (which is doubtless common enough in shallow waters near shore), Podocoryne carnea; 

 and Schizoiricha lenella. While none of these were taken with sufficient frequency to affect seriously our conception of the coelen- 

 terate fauna of the Bay, they point to the probability of considerable gaps in our original records for this group. 



