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BULLETIN 161, UNITED STATES NATIONAL MUSEUM 



So many specimens have been referred to this species that it is very 

 difficult indeed to make strict limits for the species. Undoubtedly 

 many of the forms figured here may with further studies be determined 

 to be distinct varieties or perhaps even species. So little is known in 

 regard to the distribution of these various forms, and many of them 

 have so little in the way of distinctive characters, that it is a very 

 difl&cult group to deal with. A number of the different forms with or 

 without keels in their development have been figured, and the record 

 is given in Table 9 of stations from which very similar forms were 

 obtained. Almost all these margined forms have an entosolenian 

 aperture, and probably belong in the genus Entosolenia, but as already 

 stated both typical Lagena and others have been placed together 

 here for ease in referring to them. 



Table 9. — Lagena marginata — material examined 



