4 G. LINDSTRÖM, ON TIIE SILUUIAN (i ASTUOPOUA AND PTEKOPOJ)A OK GOTLAND- 



the inollusca themselves not oiily to dittereiit genera, hut even to dilferent fiiniilies. 

 They had assumed, as it were, exactly the same sort of investtnent or shell as tlie true 

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





Oms värd' 



''oburnJSundi 



Sketck Mup of Gvilatid showtut/ the pi incijial localdies. 



have been considered till now as of the same speeies as the last mentioned. What in 

 reality are three different speeies, not even appertaining to the same genus, nor to 

 the same family, had thus been regarded as one and the same speeies, until the ana- 

 tomical structure of the animals revealed their fundamental dissimilarity. 



