BULLETIN OF THE UNITED STATES FISH COMMISSION. 31 



The average depth of the pond should, of course, be at least 3 feet, and 

 and probably a depth of 4 feet would be better in practice, as this would 

 pretty effectually prevent frost from reaching the oysters on the bottom in 

 winter, while the water would not be heated in summer as much as in shal- 

 lower })onds. The culturists abroad are said to occasionally suffer losses 

 from the water becoming too warm in their "claires" or ponds, many of 

 which get no water except once in every fourteen daj's or during spring 

 tides. From this cause also it is evident that considerable loss must be 

 experienced from evaporation, while of course the warmth and quies- 

 cence of the water would tend to cause the microsco[)ical vegetable or- 

 ganisms in the water to multiply rapidly and give oft" oxygen to the 

 water, and in turn consume the carbonic acid gas given off by the oys- 

 ters daring respiration. In this connection I must not forget to mention 

 the fact that I have known the water along some parts of the shores of 

 the Chesapeake to rise to a temperature of 101° F. to 1(»5° F., after 

 exposure to the sun during the middle of the day, where the bottom was 

 composed of dark or black mud, which would of course absorb the heat 

 from the burning rays of the sun and again radiate it into the overlying 

 stratum of water at night. 



Washington, D. C, November 24, 1883. 



10.-IVOTES OIV THE ACCI^IItlATIZATIOIV OF FISS IIV VICTORIA, ATS- 



TRAI.IA. 



By W. P. TVHBTCOrfllBE. 



[From a letter to Prof. S. F. Baird.] 



We have had a small fish acclimatization society here for some years. 

 We have stocked our waters with English trout {S. Fario), with Eng- 

 lish perch, tench, and carp. Kindred societies on the seaboard have 

 tried (with what success remains to be proved) to introduce some of 

 the migratory Salmonidw. We have not attempted this as our streams 

 are not suitable. Indeed, I may say we are very badly off" for perma- 

 nent streams in this district, most of them becoming a mere chain of 

 water-holes during the summer without any flow through them, and 

 should the fall happen to be dry it is not uncommon for the streams not 

 to run until the winter is well passed. Such dry seasons are not uu- 

 frequeut. We have in this neighborhood some small lakes which we 

 should like to stock with as good fish as we can. In some of them 

 there are already English perch and trout, and in one a fish known here 

 as the "Murray Cod" {OUgorns Macquarienfis Gunther). This fish is 

 a native of the Murray or Macquarrykion, is non-migratory, and is a 

 good table fish, but not good as a sporting fish. The hike into which 

 it has been introduced is fed by small streams which run only during 

 wet weather, and as it lowers through evaporation in summer becomes 



