104 BULLETIN OF THE BUREAU OF FISHERIES. 
attach themselves to various other fixed organisms, or directly to piles or stones. Flus- 
trella hispida forms a thick matting over the rockweed along shore, and several species 
may be found upon active living animals, such as crabs. One, indeed, makes its home 
in the gill chamber of the blue crab (Callinectes sapidus). Various minute Bryozoa may 
readily be mistaken for hydroids, or may be overlooked altogether. Thus there is little 
doubt that many such forms escaped the collectors entirely during the earlier dredging 
work of the survey. With some few exceptions, the incrusting species are the ones 
which figure most prominently in the dredging records, colonies of this sort seldom being 
absent from stones or shells. Owing to the superficial similarity of several quite dis- 
tinct species of incrusting Bryozoa, it was our practice throughout the dredging work to 
save for preservation samples of even the commonest species from every dredge haul in 
which they occurred. Only three species of Bryozoa (Bugula turrita, Crisia eburnea, 
and Cellepora americana) were regularly identified by the collectors in the field, and there 
seems to be little probability that these were confused with any less familiar forms. 
All other species, so far as detected, were preserved for future examination. These were 
later identified by Dr. Osburn, who is likewise responsible for the classification here 
adopted. 
Charts (27-46) have been prepared showing the distribution of those species which 
were recorded from 10 or more of the dredging stations.* Two of these species, Lepralia 
americana and L. pallasiana, were confused in the earlier dredging records to such an 
extent that it has been thought best to plot their combined distributions upon a single 
chart. Thus there are only 20 charts for these 21 species. 
Less of general interest is to be gathered from the local distribution of the Bryozoa 
than from that of many other groups which we have considered. Only two distinct 
types of distribution are to be found among those forms which have been dredged with 
any frequency in local waters. We have (1) species whose distribution is general, or 
without any definite restrictions throughout Vineyard Sound and Buzzards Bay; and 
(2) species found wholly, or at least predominantly, in Vineyard Sound. Not a single 
species has been found which appears to be restricted in any degree to the Bay. Thus 
the phylum has a considerably greater representation in the Sound than in the Bay. 
The average number of species taken per dredge haul ° may be tabulated as follows: 
Vineyard Sound: 
Bish Hawk statioias: 0021238 De ee eee ne aes Cae Be ae cee 3.4 
Phalarope stations) 53h. ./5405 seh in eee oi Rae ae ce ee tay 3.0 
Buzzards Bay: 
Bish ‘Hawi stations) ...2.J2.cca8 fone eioeiee ce eRe eR ie te ae 2.7 
Phalarope Stations, |. <6 sac sae icine ce eee Pee eee oe eee 2.0 
The average number of species for the Crab Ledge stations would doubtless greatly 
exceed any of these figures, but unfortunately the data are not available. 
It is highly probable that the character of the bottom has been the chief factor in 
determining the results here tabulated, just as in the case of the Hydrozoa. Reference 
to the table on page 79 shows that the average number of species per dredge haul for 
@ Including the supplementary stations of 1906-1909, for the same reason as already stated in the case of the Foraminifera 
and ccelenterates. 
> Based upon the original stations only. Were the supplementary dredgings to be considered in this computation, it is likely 
that the figures for Buzzards Bay would be somewhat greater, though it is quite improbable that they would equal those for 
Vineyard Sound. 
