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THE AM ERICA X NATURALIST. [Vol. XXXVI 1 1. 



number of experiments of this kind were tried with different 

 degrees of pressure I was not able to get any normal embryos. 

 A few abnormal embryos were reared but they lived but a few 

 days. It hardly seems that it will be possible to get any fruitful 

 results from pressure experiments on the eggs of H. solitaria 

 for these further reasons : eggs in the egg masses broken during 

 collection develop abnormally, probably because the sea water 

 gains access to them ; eggs laid in imperfect egg masses in the 

 laboratory frequently develop abnormally ; occasionally I have 



collected what appeared to be perfect egg masses and found that 

 the segmentation was very irregular, keeping these eggs under 

 observation, I found that they invariably died in a short time ; 

 some apparently normal egg masses have been found to contain 

 eggs in all stages of segmentation from the one celled to the 

 thirty celled stage. 



In brief then to summarize : The Techtibranch mollusc, first 

 descnbed b\ Sa\. and subsequently by Totten, Verrill, and 

 others, should, according to Pilsbry, properly be regarded as 

 Hamuua solitana. The dental formula is oc. i oc. The egg 



