120 BULLETIN OF THE BUREAU OF FISHERIES. 
It is to be noted that this preponderance in favor of the Buzzards Bay stations 
relates only to those of the Fish Hawk. It is in the deeper portions of the Bay, where 
the Fish Hawk dredgings were made, that the mud predominates. Elsewhere the bot- 
tom agrees more closely with that of Vineyard Sound. 
These same facts are shown by a comparison of the lists of ‘‘prevalent’’ species for the 
different groups of stations (p. 65—71),i.e., the lists of those species which were taken at 
one-fourth or more of the stations belonging to each group. Thus the list for the Fish 
Hawk stations of Vineyard Sound contains five species; that for the Fish Hawk stations 
of Buzzards Bay, nine species. The list for the Phalarope stations in Vineyard Sound 
contains five species; that for the Phalarope stations of Buzzards Bay, six species. 
With reference to the wealth of annelid life upon the three types of bottom which 
we have considered, we have the following figures, representing the average number of 
species per dredge haul: Sand, 3.4; stones and gravel, 4.7; mud, 5.2. 
To what extent the greater wealth of annelid life upon muddy bottoms is actual 
and to what extent it is apparent can not be stated. Soft mud is of course cut into 
much more deeply with the dredge than is sand or gravel, and thus a larger proportion 
of the burrowing worms would be collected from the former type of bottom, even if they 
were equally common upon both. 
Those species which were taken in one-fourth or more of the dredge hauls made upon 
sandy bottoms are: @ 
Harmothoé imbricata. Hydroides dianthus. 
Nereis pelagica. Lepidonotus squamatus. 
Diopatra cuprea. ; 
It will be seen that this list comprises exactly the same species as were recorded 
for one-fourth or more of the total number of stations. It likewise comprises the same 
species as are to be found in the lists for both the Fish Hawk and Phalarope stations in 
Vineyard Sound. 
The following is a list of prevalent species (according to the same standard) taken 
upon bottoms of gravel and stones: 
Hydroides dianthus. Harmothoé imbricata. 
Nereis pelagica. Diopatra cuprea. 
Lepidonotus squamatus. : Pseudopotamilla oculifera. 
The only one of these which was not comprised in the preceding list is the last one 
named. 
The corresponding list for muddy bottoms is as follows: 
Hydroides dianthus. Harmothoé imbricata. 
Diopatra cuprea. Ninoé nigripes. 
Nephthys incisa. Cistenides gouldii. 
Clymenella torquata. 
Three of the foregoing species (Hydroides, Diopatra, and Harmoihoé) were comprised 
in all of the preceding lists, and indeed they may be regarded as almost ubiquitous in 
local waters. The other four are to be regarded as characteristic of muddy bottoms, 
and indeed all of the seven appear among the ‘‘prevalent”’ species for the Fish Hawk 
@ In this and all similar lists, the species are arranged in the order of frequency. 
