In Plrte I, an early photograph shcaTS the foiir cval basins, 

 previously described in the 1945 report of the Biological Station? 

 the second photograph shoT.'s one of the basins in operation iirith ■ . 

 larvae. 



The Boothbay Harbor type of tank is a wooden box 18'' x 18" x 18" 

 in v;hich the v/ater enters tlirough the botton and flo'Ts avray.in an 

 over-flow situated in the upper parto These tanks are able to rip.nage 

 the rearing of 3,000 larvae while the oval tanlcs illustrated in 

 Plate I are able to take 15,000 to 25,000 larvact The econojnic 

 factor concerned in such a rearing establisliment is the daily consump- 

 tion of water. We have found four tines in the course of a season the 

 output of water of the different t.T,Tpes - of rearing basins. Here are 

 the average results of our observations: :' 



Tanlcj Boothbay Harbor type: 93 gallons per hour 



Tank, oval ' 332 " " " 



The six rearing tanlcs in operation consuiue 1,514 gallons an 

 hours that is, 36,336 gallons per 24 hours of operation. 



Larvae hatched and enplo ye d in rearing; 



In the course of the seasonp 17.7,490 larvae fr.on the hatching 

 troughs have been taken care of for the purpose of rearing. These 

 larvae came from 55 females confined in the troughs especially con- 

 structed to collect rapidly the young larvae after their hatching. 

 In Plate II, one sees a. photograph showing one of these troughs with- 

 out its covers and one other showing it in operation? that is to say, 

 xiith its covers. Note that ^during the hatching the females are kept 

 in darkness o 



The hatching period is extended for seven weeks, namely froia the 

 1st of July to the 19th of August* The height of the hatching has 

 occurred during the second week of Julyj indeed during that \7eek 

 alone-, 39 per cent of the larvae hatched. In Table III one can see 

 the number of larvae hatched and used for rearing. 



This prolonged, hatching period has permitted the distribution 

 of the rearing into 11 groups, 8 groups in the oval taiilcs and 3 groups 

 in the type of tank in use in Bootjlribay Harbor. ; 



Plate I - Roaring tan];s 



L) The tanks in operation v/ith the exception of if^. 3© 



llote in the backgroujid at the right the two bolting 

 cloth nets used for counting; these, nets carry checker- ■ 

 work to facilitote the- work. The arrangei.ient in batter- 

 ies of the tvj-o tanks permits the utilization of a coJm.ion 

 drains 



2G 



