1890.] NATURAL SCIENCE.S OF rillLADKLI'Iir A. o^O 



distribution of the littoral p]('hiiioderin« in the Western tropical 

 Atlantic region. 



A paper by Mr. H. F. Nachtrieb' upon the Echinodernis col- 

 lected at Beaufort, N. C. in connection with the Marine Labora- 

 tory of the John Hopkins University, throws some light upon the 

 question of the northern limit of the West Indian p]chinoderm shore 

 fauna. Of the three species of starfish collected, two belong to the 

 West Indian fauna and one to the northern ; of the Ophiurans the 

 three species are all West Indian ; of the sea-urchins three species 

 are West Indian and one northern. The Holothurians are uniden- 

 tified. Thus it is seen that at Beaufort, which is about 70 miles to the 

 southeast of Cape Hatteras, the Echinoderm fauna is distinctly 

 West Indian. 



Commander Bartlett'^ of the United States Coast and Geodetic 

 Survey, in connection with the work of the steamer " Blake" has come 

 to the conclusion that the Arctic or Labrador current does not ex- 

 tend south of Cape Hatteras, but at that point goes under the Gulf 

 Stream and to the eastward, being deflected that way by the form 

 of the Blake plateau. He also states that the Gulf Stream has for 

 its western bank the 100 fathom curve wdiich is on an average about 

 70 miles from the shore as far north as Cape Hatteras, and that the 

 water inside of the 100 fathom line to the shore, appears to be an 

 overflow of the stream as the temperature to five, ten and fifteen 

 fathoms is nearly as high as that found in the stream. North of 

 Cape Hatteras the Gulf Stream is deflected northeastwards and is 

 separated from the coast by the cold Labrador current. It will be 

 apparent from the above statements that Cape Hatteras marks 

 the northern limit of an area of temperature which may be regarded 

 as essentially that of the West Indian littoral region. 



The following list of species collected by the Exi)editioii will 

 readily show their distribution. 



Holothuria Heilprini. ^ 



Holothnria Sllamensis. ^ Port of Silam, northern coast of Yucatan. 



Holothuria nitida. ) 



Diadema setosum, West Indies, Cape Florida to Fernando de 

 Noronha. 



1 Notes on Echinoderms obtained at Beaufort, N. C, Johns Hopkins Uni- 

 versity. Studies from the Biological Laboratory, Vol. iv. p. 81. 



2 Report of the United States Coast and Geodetic Survey, 188l2, p. 37 and 

 " Three cruises of the Blake" by Alexander Agassiz p. 257, fig. 176. 



