4 G. LINDSTROM, UN THE 8ILUKIAN (i A.STR<JP01)A AND PTEKOPODA UK GOTLAND- 



the inollusca themselves not only to different genera, hnt even to different families. 

 They had assumed, as it were, exaetly the same sort of investment or shell as the true 

 Marginella glabella, only differing in trifling and easily overlooked details, so as to 





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have been eonsidered till now as of the same species as the last mentioned. What in 

 reality are tliree different species, not even appertaining to the same genus, nor to 

 the same tainily, had thus been regarded as one and the same species, until the ana- 

 tomical structure of the animals revealed their fundamental dissimilarity. 



