U. S. B. F.— Doc. 890. 



mm 



OYSTER WITH RIGHT SHELL AND MANTLE REMOVED. 



'^■r^u"^■ ^■nt^;;ioo'?1'5,*°'' "'"!f'^\'^"- ^"'"''^'^ °^ ^e^-^: D- digestive gland or liver; G.. 

 gills, I., intestine; M.. mantle; Mo., mouth; C. oesophagus- P palos • R recroduc- 



Na1u%rHisto7y'P'''= ^- ^'"'"''' °^ '"^^'' (Photo^from American Museum of 



