JOURNAL OF MICROSCOPICAL .SCIENCE. 



DESCRIPTION OF PLATE VII, 



Illustrating Mr. Hougliton^s observations on the parasitic 

 nature of the Fry of Anadonla cygnea. 



rig. 



1. — Glochidium-larvse attached to the tail of the Stickleback. 



2. — Pront view of a Glochldium. 



3. — Side view; valves partially opeu. Both of these, though still enclosed 

 in the egg-membrane, show the bysbus-filameut (a) distinctly. 



4. — Glochldium^ with the valves fully open, showing the adductor mus- 

 cle («). 



5. — Side view of the same, showing the mode of origin of the byssus- 

 filament («) 



6, — A more magnified figure in the same position, showing the three pairs 

 of tentacular organs noticed by Carus {a) 



7. — One of the latter, x 100, to show its resemblance to a wetted camel's- 

 hair pencil. 



