66 Papers from the Department of Marine Biology. 
The absence of suitable bottoms at the Tortugas undoubtedly 
accounts for the absence of some of these, as Luidia senegalensis, 
Moira atropos, and Thyone briareus; but it is probable that most of 
them will ultimately be found there, when our knowledge is more 
complete. It is noteworthy that of the 69 Florida species, 32 (or 
almost one-half) are not known from Tobago, while 20 are as yet 
unrecorded from Jamaica and 27 are not listed from St. Thomas. 
While our knowledge is as yet too imperfect to make deductions very 
safe, the increasing difference in the faunas as the distance from Florida 
increases is so obvious and so regular that it can not be overlooked. 
One other feature of the Florida fauna must be mentioned. More 
than a third (24) of the species occur on the coast north of Florida, 
but not one of these has peninsula Florida as the southern limit of its 
range and only one, Amphioplus abditus, reaches its southern limit at 
the Tortugas. At least one echinoderm, A sterias forbesii (Desor) occurs 
on the coast of Florida, finding the southern limit of its range there, 
but as this species does not occur at Tortugas or Bermuda and is a 
distinctly northern species, it is not included in the tables. 
THE TORTUGAS. 
No fewer than 76 littoral echinoderms occur at the Tortugas. 
Perhaps 4 or 5 of these are not so strictly littoral as my restrictions 
require, but there are certainly more than 70 species which may be 
collected at the Tortugas by hand, without trawl or dredge. Thus 
the seat of the Carnegie uaboratory is apparently the best place in 
the West Indies for this particular sort of fauna. Four of the species 
are as yet known only locally and 6 are tropicopolitan, 35 are of the 
Tropical Atlantic group, 13 are distinctly West Indian, and 18 are 
northern. There are 56 species that the Tortugas have in common 
with Florida, 52 in common with Jamaica, 47 with St. Thomas, and 45 
with Tobago. Only 19 species, just one-fourth, occur on the mainland 
coast north of Florida. 
BERMUDA. 
The echinoderm fauna of Bermuda has been quite thoroughly 
collected and studied during the past 30 years and is probably better 
known to-day than that of any other area in the region under con- 
sideration. There are 42 species here listed which occur there, and 
there is at least one unidentified holothurian not included herein. 
Of the 42 species, 1 is endemic and 4 are tropicopolitan, 4 are northern, 
6 are West Indian, 1 is Mediterranean, and all the rest (26) have a 
wide distribution in the tropical Atlantic. It is rather remarkable 
that the ophiuran fauna is somewhat scanty, without an endemic 
species. Both at the Tortugas and Tobago more than half of the 
echinoderms are brittle-stars, while at Bermuda they comprise less 
than 43 per cent. Of the 42 echinoderms found at Bermuda, 34 occur 
at the Tortugas, 34 at Jamaica, 32 at Tobago, 26 at St. Thomas, 
