PHYLUM MOLLUSCA 



247 



D 



D 





3. 





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©OO 



Fig. 138. — "Egg masses of common snails. A, Lymnaea (fresh-water; gelatinous 

 mass); B, Heliosoma (fresh-water; gelatinous mass); C, Physa (fresh-water; 

 gelatinous mass) ; D, Pleurocera (fresh-water branchiate; tough gelatinous mass) ; 

 E, Polygyra texasiana (terrestrial; eggs in cluster) ; F, egg capsules of Busy con. 



Qoniobasis comolenfis 

 (Pleuroceridae) 



Coivpeloma decisum 

 (Vwiparldoiz) 





Amnicola comolensis 





CochliopQ texana 

 (Amnicolidae) 



Fig. 139. — Some common fresh-water branchiate snails. 



