SCIENTIFIC RESEARCH 



251 



G.TKIlNE 



Fig. 28. Fresh-water Mussel, Lampsilis subrostrata, and Developmental 

 Stages. Above, the gravid female showing fan-shaped brood-pouches (a 

 portion of outer gill). Middle, side and end views of the glochidium larva 

 greatly magnified. Many thousands of these larvae would be found in 

 each brood-pouch. The groups of hair-like projections on the figure to 

 right are sensory organs. The fibres of the muscle by which the valves of 

 the glochidial shell are clamped upon the gill filament of a fish appear at 

 the bottom. Below, four views of a young Lampsilis which has recently 

 begun life upon the bottom after its parasitism on the fish. The outline 

 of the glochidial stage is still seen upon the shell which is growing rapidly. 

 The animal moves actively by means of the "foot" which is thrust from 

 between the valves of the shell. (After Lefevre and Curtis.) 



