I08 REPORTS ON INVESTIGATIONS AND PROJECTS. 



BIOLOGY, MARINE. 



MARINE BIOLOGICAL LABORATORY AT TORTUGAS, FLORIDA * 



By a. G. Mayer, Director. 



On October 15, 1904, the laboratory yacht Physalia started 

 southward from New York under command of the director. The 

 yacht's behavior in a storm off Cape Cod had demonstrated the 

 necessity for lightening her keel and for after ballast; and con- 

 sequently the iron keel had been replaced by one of oak, shod with 

 iron, and a large fresh-water tank was placed in the after hold. The 

 advantages of these changes were apparent in the hurricane of No- 

 vember 13, 1904, when the Physalia survived with only the loss of 

 her jib. while all of the vessels in her neighborhood were driven 

 ashore. 



The course southward ]a\- out along the New Jersey coast, up 

 Delaware Bay, through the Delaware and Chesapeake Canal, through 

 Chesapeake Bay, the Dismal Swamp Canal, Pamlico Sound, out at 

 Beaufort, North Carolina, stopping at Bogue Inlet, Winyah Bay, 

 and Charleston, then through inland passages to Beaufort, South 

 Carolina, then seaward to Sapello Sound and Brunswick, Georgia, 

 inland to Fernandina, seaward to St. Johns River, St. Augustine, 

 and finally to Miami. Florida, where the yacht arrived in good 

 order on January 23, 1905, 



Surface hauls were made with the tow nets upon all possible 

 occasions in order to take advantage of the opportunity afforded 

 for the determination of the relative abundance and the difference 

 in character between the pelagic animals of bays and inclosed waters 

 such as Long Island Sound, Delaware and Chesapeake bays, Pam- 

 lico Sound, etc, and the open ocean. Colored drawings were made 

 from life of all new or interesting Medusse, Siphonophorse, and 

 Ctenophorae. 



It may be briefly stated that while the pelagic fauna of bays and 

 inclosed waters is rich in individuals, it is poor in variety of species 

 when compared with the open ocean. Certain forms such as the 

 ctenophore Mnemiopsis or the hydromtdnsdiGlossocodon tenuirostris, 

 are exceedingly abundant in inclosed areas, even in brackish water, 

 while others, such as Nemopsis hachei, thrive only near the mouths 

 of bays, where the sea-water enters quite freely. The vast majority 

 of i)elagic animals that are carried into bays and inclosed waters 

 are quickly killed, and are found in a more and more damaged condi- 



* Grant No. 219. $15,700 . (For first report see Year Book No. 3, pp. 50-54. 



