528 XJ. S. BUREAU OF FISHERIES 



tail-and-foot disease, which in the past has destroyed from 17 to 35 

 per cent of the total brood. Experiments carried out by Dr. H. F. 

 Prytherch for the purpose of finding a practical cure for this malady 

 show that copper is very effective not only in checking the disease 

 but also in permitting regeneration of the infected tissues. In the 

 early fall the disease soon assumed epidemic proportion and ap- 

 peared in the form of rapid growing lesions of the tail, feet, skin, 

 and eyes of the young terrapins. Various methods of disinfection 

 were tried. The rearing troughs were regularly disinfected with 

 various concentrations of formalin, and a strong solution of salt 

 brine, while the infected terrapins were isolated and treated with 

 dilute solutions of copper sulphate, aluminum sulphate, formalin, 

 and sodium thiosulphate. 



In the two control lots there was a loss of over 94 per cent of the 

 terrapins after a period of 10 weeks. On the other hand, those 

 treated with copper sulphate showed in the same length of time a 

 total loss of only 8 per cent. In the aluminum sulphate, formalin, 

 and sodium thiosulphate solutions there were losses of 20 per cent, 

 15 per cent, and 22 per cent, respectively. Though each of these four 

 solutions checked the rapid growth of the disease, its complete 

 elimination was evident only in the lot of terrapins treated with 

 copper sulphate. A careful examination on November 10 of the 

 terrapins treated with copper showed that every single individual 

 had completely recovered from lesions affecting the eyes, tail, and 

 feet and had grown a new layer of skin over the injurecl tissues. 



Diseased terrapins from the numerous rearing compartments were 

 also placed in a large copper-lined tank in the hope that this might 

 prove a practical method of combating the disease. The animals 

 placed here exhibited remarkable improvement in a few days and 

 showed after a period of three months a loss of only 13 out of a 

 total of 146 infected individuals. Since metallic copper apparently 

 gave off enough free ions to produce a beneficial effect, a small piece 

 of sheet copper 2 inches square was placed in each rearing compart- 

 ment. Noteworthy results have followed this simple procedure, as 

 evidenced by the fact that the loss of young terrapins has steadily 

 decreased, from 103 in September to 27 in October, 21 in November, 

 and only 8 in December. The records of terrapin mortality for 

 1930 are much higher than for the present year and show a loss of 

 41 out of a total of 7,028 in November and 26 out of a total of 6,987 

 in December, while for the past two months there has been a loss 

 of only 21 out of 12,022 in November and 9 out of 12,001 for 

 December. It is probable that the rapid recovery of the terrapins 

 in the presence of copper is due not only to the bactericidal action 

 of this element but also to a possible deficiency of copper in the diet 

 for blood formation as a result of keeping the animals in confine- 

 ment. 



A report covering all terrapin-cultural activities carried on since 

 the preparation of the last general report in 1927 (Review of Ex- 

 periments on Artificial Culture of Diamond-Back Terrapin, by 

 Samuel F. Hildebrand, Bulletin, U. S. Bureau of Fisheries, Vol. 

 XLV, 1929 (1930), pp. 25 to 70), was prepared during the year. 



Shore fishes of North Carolina. — The studies of the development 

 of fish eggs and young fish, undertaken several years ago, was con- 



