RKPORT OF COMMISSIONER OF FISH AND FISHERIES. 119 



huinaii system, aud a ^'cry lilx'ial iiiargiu may be allowed in favor of 

 the former. In fact, it is probable that a very large percentage of what 

 might ordinarily be regarded as impurity in potable water is more 

 beneficial than harmful to oysters. When* the amount of free ammo- 

 nia in ])otable water exceeds 0.01 it is generally considered to be due to 

 recent sewage contamination, and the amount of albuminoid ammonia 

 in a safe drinking-water sliould not much exceed 0.015 parts per 100,000 

 parts of the water. The figures furnished by Mr. Neher's tests may be 

 summarized as follows: At the mouth of the Connecticut River, .005 of 

 free ammonia and .013 of albuminoid ammonia; on a line across the 

 Sound opposite the mouth of this river, .002 and .015, respectively; a 

 second line somewhat further west, .005 and .01; a line o])i)osite Matini- 

 cock Point, .01 and .01(1; at Throgs Neck, .023 and .018. The last two 

 undoubtedly show the influence of the East River. On and near the 

 dumping-grounds oft' New Haven, Bridgeport, Norwalk, and Stamford 

 the amount of free ammonia ranged from .000 to .013 and the albu- 

 minoid ammonia from .011 to .010. These dumping-places have always 

 been regarded as the most serious menaces to the oyster-grounds in 

 Long Island Sound, but the chemical observations fail to support that 

 claim. In New Haven Harbor the free ammonia amounted to .013 and 

 the allniminoid to .018, while in Bridgeport Harbor they were .02 and 

 .018, respectively. 



The results of analyses made in three other bodies of water may be 

 noted here for the sake of comparison, the first figures given in each 

 case being those for the free and the last for the albuminoid ammonia, 

 as above. Lake Ontario, 0.002 to 0.004 and 0.013 to 0.020 ; Oneida Lake, 

 0.001 to 0.008 and 0.015 to 0.024; Thames River, England, 0.004 to 

 0.176 and 0.028 to 0.035. 



It may, therefore, safely be concluded that so far as regards organic 

 impurities, the oyster beds in Long Island S(mnd are in no immediate 

 danger from that cause. The results of the dredging work also sup- 

 port this conclusion, tlie animals taken of all kinds being generally in 

 a good and healthy condition. 



Life histori/ of the starfish. — In connection with the investigation 

 of starfish depredations, a si)ecial study of the embryology and life 

 history of this species was begun at Woods Holl Station during the 

 summer of 1889 by Prof. W. K. Brooks, of Johns Hoi^kins University, 

 and was again taken up during the season of 1890, by one of his assist- 

 ants, Mr. George W. Field. Both of these biologists have published 

 brief notices of their preliminary results in the Johns Hopkins Univer- 

 sity circulars, vol. x, No. 88, 1891.* This inquiry will be continued in 

 subsequent years, and it is expected that some conclusions may be 

 reached which will be of considerable practical importance. 



** On the ojirly stages of Ecliinodcrnis; l»y W. K. lU-ooks. Contributions to the 

 embryology oi Asterias rulyarin {ForbesH); by George W. Field. 



