DEPARTMENT OF MARINE BIOLOGY. 135 



was ascertained that numerous species of corals were sharply limited in their 

 distribution, but no attempt will be made to formulate the determining fac- 

 tors until the collections have been carefully studied. 



A considerable amount of experimental work was_ initiated on the Tortugas 

 in the hope of obtaining information on several subjects. 



Rate of grozi'th. — As manv corals grow on the concrete piers of the Gov- 

 ernment dock off Garden Key, an excellent opportunity is afforded for ob- 

 servations on the rate of grov/th of the species there represented. Measure- 

 ments were made on the following species, and they will be observed from 

 year to year: Ociilina sp., Eusmilia knorri,Mamcina gyrosa,M(eandra clivosa, 

 Agaricia agaricites, Pontes porites var. 



Fort Jefferson is surrounded by a moat to which the sea has access. The 

 water in this moat is usually sluggish, and although during periods of heavy 

 rain its degree of salinity is less than that of the ocean, several species of 

 corals grow in it. Individuals of these were selected for growth observations. 



Transplanting specimens. — Specimens of Mccandra clivosa, which habit- 

 ually grow on the outer side of the piers of the Government dock, where the 

 light is strong, were removed from the outer piers and attached to the inner 

 piers so as to observe the effect of the change in environment. 



Specimens of Oculina sp., Eusmilia knorri, Orbicella annularis, Favia 

 fragum, Mceandra labyrinthiformis, M. areolata, M. clivosa, Porites porites 

 var., were taken from the outside and planted in the moat. They were meas- 

 ured, and will be kept under observation. 



Rearing corals from the young. — Specimens of the following species were 

 found growing on the reefs off the western side of Loggerhead Key, opposite 

 the light-house: Orbicella annularis, Faz'ia fragum, Mccandra clivosa, Agari- 

 cia agaricites, and Porites astreoides. Live specimens of Orbicella annularis, 

 Favia fragum, Agaricia agaricites, and Porites astreoides were brought into 

 the laboratory and kept under observation. Specimens of Favia fragum and 

 Porites astreoides were extruding planulse. These were allowed to settle on 

 pieces of glass placed in the vessel or on the bottoms of the vessels themselves. 



Porites astreoides. — Planulse were extruded the night of May 3, 1908, 

 attached probably the night of ]\Iay 10. On May 27, igo8, the calice, accord- 

 ing to information furnished by Dr. Mayer, measured 2.5 mm. in diameter. 

 This individual subsequently died. 



Favia fragum. — Planul^ were extruded on the night of May 6, 1908. Dr. 

 Mayer, subsequent to my departure from the Tortugas, continued observa- 

 tions on the planulse and the attached young. 



1 attached May 11, 1908. 



o attached May 12 and 13, 1908. 



40 attached May 14, 1908. 



12 attached May 15-17, 1908. 



2 attached May 18, igo8. 



On July 22, there were 6 young corals in the dish. Four of these were 

 single calices and 2 were double, due to the fusion of 4 originally separate 

 polyps. The dimensions of the individuals were as follows : 



(a) Single calice 5 mm. in diameter. 



(b) Single calice 4 mm. in diameter. 



(c) Single calice 4.5x4mm. 



(d) Single calice 4.5 mm. in diameter. 

 (e -h f) Double calices 5.5 x4.5 mm. 



(g) Double calices 4x3.5 mm. 



