DEPARTMENT OF MARINE BIOLOGY. 181 



Since in all probability the learning curves of these groups will show very- 

 different forms, it is planned to allow the group shooting 80 arrows per day 

 to shoot 5 times with the rifle ; and the group shooting 5 arrows per day to 

 shoot 80 times per day with the rifle, etc. In this way individual variations 

 may be eliminated and the pure effects of frequency and amount of practice 

 arrived at. 



Nesting Instincts of Noddy and Sooty Terns, by K. S. Lashley, 

 Johns Hopldns University. 



The question of proximate orientation of the noddy and sooty terns was 

 studied. Watson, 1908,* carried out some experiments which indicated 

 that the recognition of the nest-locality by these birds is extremely accurate, 

 but he did not determine exactly the sensory data involved in the adjust- 

 ment. The work of this season was directed toward the solution of this 

 problem and enough data have been collected to show that the adjustment 

 is almost wholly visual, although the reaction is very complicated. 



In connection with proximate orientation, the recognition of the young 

 was studied. The noddies gave no evidence that the young are distinguished 

 one from another, or even from the young of the sooties. The sooties, 

 whose nesting habits made such a recognition imperative, do not at first 

 distinguish their OAvn from the young of other sooties. About 8 to 10 days 

 after the eggs hatch, however, they begin to recognize their own young, at 

 first imperfectly, later more surely. There is evidence that the recognition 

 is based rather upon the behavior than the appearance of the young birds. 



It was found possible to modify the behavior of the birds by exchanging 

 older for younger chicks, chicks for eggs, etc., and to change the duration of 

 the laying and incubation periods to a considerable extent. 



The Reef Corals of Southern Florida, by Thomas Wayland Vaughan, 

 U. S. Geological Survey. 



During May and June, while at the Tortugas, the measurements and 

 records of coral colonies under observation to ascertain the rate of growth of 

 the different species were continued. The studies of growth-rate have made 

 satisfactory progress, as a number of colonies known to be three years old 

 are steadily growing; other colonies, planted or naturally attached, have now 

 been under observation for periods ranging from two to five years. Some 

 naturally attached colonies of branching species of Porites have begun to 

 disintegrate because of boring organisms perforating their bases. The 

 growth records, which are too numerous for even a resume of them to be 

 given in this report, are kept in tabulated form and will later be published. 

 In addition to the studies mentioned considerable advance was made in 

 platting the position of reefs, coral patches, and more isolated colonies on 

 the maps of the area. 



The assembling of data bearing on the ecology of the species of corals 

 living in the waters of southern Florida has been continued. Dr. H. F. 

 Moore, of the Bureau of Fisheries, has furnished complete tables of tempera- 

 ture records based on readings at the principal light-houses along the line of 

 the reefs. These records give for each station the average temperature in 

 periods of 10 days and the maximum and minimum in the series of years 

 over which the 10-day periods extend. As Dr. Mayer has conducted experi- 

 ments to ascertain the upper and lower vital temperature limits of the 

 common shoal-water corals of Florida, the temperature relations of these 



♦Watson, J. B., 1908, The Behavior of Noddy and Sooty Terns. Papers from the 

 Tortugas Laboratory, vol. ii, Carn. Inst. Wash. Pub. 103. 



