281 



green top material consisting chiefly of Microcystis aaruginosa; with 

 some Anuriea cochlearis; Lyngbya sestuarii, Microsystis aeruginosa; 

 Bulbochsete, bristle; Coelastrum microporiim; Meris7nopoedia glauca; 

 Pediastriim boryanum; Diatoms — Navicula, Coscinodiscus ; etc. 



Measurements : — 



The following is a series of measurements of Lost Lake examples : 



Measurements in mm. 



Eemarks. 

 Fanshaped female. 

 Fanshaped female gravid. 

 Fanshaped female. 

 Fanshaped female. 

 Fanshaped female. 

 Male. 

 Male. 

 Male. 

 Male. 

 Male. 

 Most of these shells. 

 blistered posteriorly. 

 The males are fairly like those of river examples; the females are 

 more fan-shaped. Weight of the 10 shells, 15 oz. ; only a few are rayed. 



11. Lampsilis ventricosa (Barnes). Pocket-book. 



Rather common at the Long Point mussel bed; a few found in the 

 bed by Farrar's and a few in Lost Lake. The species as found in the 

 lake is markedly dwarfed and quite different in appearance from the 

 usual river form. There are two types in the Long Point bed, one con- 

 sisting of females and having the post-basal inflation of the shell char- 

 acteristic of that sex, not exactly as in the river form, however, but 

 somewhat more restricted; this feature, along with a peculiar stain ct 

 the epidermis which conceals the normal coloring of the shell, causes 

 them to resemble very closely a short female L. luteola. The other type, 

 an oval shell without the post-basal inflation, was at first taken to 

 represent the males, but some of them were found to contain glochidia. 

 These, too, bear a marked resemblance to L. luteola, and the only way 



