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Morphology of Cordylophora : — a, hydrosoma of Cordylo- 

 pkora lacustris, growing on a dead valve of the swan-mussel ; b, 

 longitudinal section of a portion of its ccenosarc, with a single 

 polypite ; c, another fragment of the same ccenosarc, to which 

 are attached, a polypite, and three reproductive bodies, or gono- 

 pliorcs, in various stages of development, the largest and most 

 advanced containing ova; — o, mouth; 5', cavity behind the 

 mouth ; 5, gastric cavity ; «', interior of the ccenosarc ; fv, endo- 

 derm ; /it, muscular layer; (k, ectoderm; €«', outer hard layer, 

 or polypary, excreted by ectoderm ; ex", processes of ectoderm, 

 connecting it with the inner surface of this hard layer. (All, ex- 

 cept a, magnified.) 



