l'.ii.i,. II. S. !'■. I'"., [919-20. 



I'i,.\Tr; XX. 



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Juveniles of 20 sjwcics of mubscU found in the artificial |xmdi> at the U, S. Fisheries Bioloicieal 

 Station within two years from the time of construction of the ponds. Reading from left to ri«hl 

 these are: 



Top row: Atuidtmta imhcctUti. Ano(i<mta ofrpuUnla. Amxiunta suhorhiculata, Arcidens am/raootut. 



Second row; Strophtiui edcntulm .Symphynota cotnplanata, LamPsilii alata. Lamp alts laeiisiima. 



Third row: Lampiilts capai, /,ampiilti tjracilii, Lampitln lenlricoiu. Lampiitti luUola. 



Fourth row: I^ampalti iuhroitrata. Lampulti paria. /,ampiHti Ityamentma, (Jhmana rlliP$ii. 



Fifth row: J^laijvila d-miut/'frmti, Obltf/uarta rejlcxa. Qum/rula plicata, Quadrulu undaia. 



AH rcprodudd natural size excepting the two ri«ht-hand fiifures in tfjp row which arc reduced 

 one-half. {Pholo«raphcd by J. B. Sfjuthall.) 



