THE MIERICAN SPECIES OF SPHYRADimi WITH AN IN- 

 QUIRY AS TO THEIR GENERIC RELATIONSHIPS. 



By G. Dallas Hanna, 



Of the United States Bureau of Fisheries, Washington, D: C. 



Land snails belonging to the genus Sphyradium are found in those 

 parts of Europe, Asia, and North America generally designated 

 as Holarctic. One species extends into the Neotropical realm, and 

 two forms which, by the shell, apparently belong to the genus, are 

 found in the Hawaiian Islands. 



As the shell is distinctly Pupillid in character the group was orig- 

 inally included in the family Pupilhdas (or Pupidse), but when the 

 jaw and radula became such factors in the classification of the land 

 snails, the genus was removed from this family and of late years 

 it has been placed along with Punctum in a subfamily of the Endo- 

 dontidse, one of the divisions of the Aulacopoda. 



Some live animals of Sphyradium edentulum ( Vertigo simplex Gould, 

 of Binney and others), were recently received from Caribou, Maine, 

 collected by Mr. O. O. Nylander. A study of this material in con- 

 siderable detail has revealed the fact that the form, by lacking pedal 

 grooves, does not belong to the Aulacopoda and all the other anatom- 

 ical characters other than those of the jaw and radula show that 

 it is closely allied to the genus Vertigo of the family Pupilhdse. 



The genus was removed from the PupilUdse by Sterki ^ upon the 

 structure of the radula. The jaw is by Sterki stated to be composed 

 of numerous separate plates loosely joined together in a arcuated 

 series. This is the condition of the jaw in Punctum and for this 

 reason the two genera have been placed together in the Endodontidse. 

 According to Lehman,^ however, the jaw is constructed of a single 

 piece and the radula is but slightly different from what is found in 

 Vertigo, 12 — 1 — 12, teeth in a transverse row. Different investi- 

 gators seem to have obtained different results in their w^ork on these 



1 sterki, Nautilus, vol. 10, 1896, p. 75. 



2 Lehman, Lebenden Schnecken und Muscheln der umgegend Stettins und in Pommem, 1873, p. 142, 

 pi. 14, fig. 49. 



Proceedings U. S. National Museum, Vol. 41— No. 1865 



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