122 BULLETIN OF THE BUREAU OF FISHERIES. 



With a very few exceptions the last two lists comprise species which primarily 

 inhabit muddy shores and bottoms. In the case of certain species {Clymenella and 

 Rhynchobolus) it is to be noted that the few records of their occurrence in Vineyard 

 Sound refer to areas whose bottoms are known to be partially muddy. This type of 

 distribution is not, however, wholly intelligible in the case of Clymenella torquata, since 

 it is known to occur in abundance in shores of pure sand. Unlike most of the foregoing 

 species, Pista palmata and P. intermedia appear to be restricted, both in the Bay and 

 in the Sound, to the adlittoral zone. They are found upon various types of bottom, 

 including muddy ones. Platyncreis megalops might perhaps have been included in 

 the last of the foregoing lists, since it was recorded more frequently (absolutely as well 

 as relatively) from Buzzards Bay. Like the two species of Pista, it was taken much 

 more often at the inshore stations. 



As the last of our groups with respect to distribution, we have : 



Species exhibiting no evident preference for one or ilie other body of wafer. 



Number of stations. 



Nephthys bucera 6 Sound4- 5 Bay. 



Marphysa leidyi 7 Sound + 5 Bay . 



Diopatra cuprea 105 Sound+86 Bay. 



Arabella opalina 27 Sound + 17 Bay. 



Parasabella microphthalmia 6 Sound + 6 Bay. 



Hydroides dianthus 130 Sound +93 Bay. 



The distribution of most of these last species seems to be entirely independent of the 

 character of the bottom. Two of them (Diopatra and Hydroides) are among the most 

 ubiquitous of our local Annulata, though it is possible that the distribution of Diopatra 

 is not so general as the wide-spread occurrence of its tubes would lead one to suppose. 

 Regarding three of the foregoing species the records are too meager to permit of our 

 forming any conclusions of value. Nephthys hucera is probably not of general occur- 

 rence in the Bay, since it is known to be predominantly a sand-dwelling species. 



The temperature factor, which has been shown to be such an important one in 

 determining the distribution of many species belonging to other groups of organisms, 

 probably applies to certain of the local annelids, though it appears to play a relatively 

 insignificant part with respect to the species for which charts have been plotted. The 

 only case among the latter which seems to fall under this head is that of the serpulid 

 worm Hydroides dianthus. The absence of this species from the western portion of 

 Vineyard Sound is a conspicuous feature in its distribution, especially when coupled 

 with the fact that it has not once been recorded from Crab Ledge, despite the favorable 

 bottom at the latter point. It is of probable significance in this connection that 

 Hydroides is predominantly a southward-ranging species, which may, on this account, 

 be poorly adapted to the colder waters of the region. The case resembles that-of the 

 coral Astrangia (p. 99) and that of the sea urchin Arbacia (p. 113), which have already 

 been discussed from this point of view. So far as our records go, however, there are in 

 Vineyard Sound none of those characteristic cold-water species which are confined 

 to the neighborhood of the open ocean. But there are a number of species of annelids 

 recorded from the Crab Ledge stations alone among the dredgings of the surv^ey. For 

 most of such species Cape Cod is believed to lie at the southern limit of distribution. 

 Some of these are included in the following table. The statements as to range have 

 been furnished us by Dr. Moore. 



