EDGAR ALLEX. 



mentation was afforded, this supply was much clearer than water 

 from the river or reservoir. The fact that very successful yields 

 were obtained in artificial mussel culture experiments carried on 

 simultaneously under these conditions by Dr. A. D. Howard and 

 B. J. Anson excludes any possible intervention of adverse en- 

 vironmental conditions. 



OBSERVATIONS. 



Between July 15 and 20 about two dozen mussels were ex- 

 amined without finding a gravid individual. On July 24, 5 of 

 33 examined (15 per cent.) contained early embryonic stages. 

 Nineteen of these 33 were observed repeatedly until September 

 i. On July 31,8, including the five already noted (42 per cent.), 

 contained embryos. On August 4, 17 or 89.5 per cent, were 

 gravid. Larger numbers of this species were examined during 

 August. From August 8 to September I the percentage of mus- 

 sels bearing embryos, glochidia, or young in various stages of 

 metamorphosis never dropped below 77.2 per cent, (see Table 

 I. and Graph I). 



TABLE I. 

 PERCENTAGE OF MUSSELS BEARING EMBRYOS OR GLOCHIDIA. 



80 



20 



20 2V 

 July 



31 4 



15 



22 



28 I 



5ef>t 



GRAPH i. Percentage of mussels bearing embryos or glochidia. 



