114 THE NAUTILUS. 



wliorl for a short distance above. Opercuhim as usual in the genus. 

 Length 3.2, diam. 2.2, longest axis of aperture 1.6 mm. 



A small stream near St. Augustine, Florida. Types no. 58088, 

 A. N. S. P., collected by Charles W. Johnson. 



This species is larger than A.Jloridana Ffld., with a longer spire 

 and more obtuse apex. It was collected in some quantity by Mr. 

 Johnson many years ago. It was at first identified as BythineUa 

 tenuipes Couper, and so recorded in Nautilus iii, p. 137 ; but fur- 

 ther investigation has shown that it belongs to a different group of 

 species. 



NOTES ON THE NOMENCLATURE OF THE PUPACEA AND 

 ASSOCIATED FORMS. 



BY vr. II. DALL. 



The publication of Mr. Woodward's list of British land shells and 

 certain work on which I have been engaged, have recently drawn 

 my attention to this subject, which I have found so involved and so 

 imperfectly represented in many publications on the group as to lead 

 me to a tolerably thorough investigation, some of the results of which 

 are here expressed. 



I take it as axiomatic that (1) the type of a group must be one of 

 the species mentioned when the name of the group was first pub- 

 lished ; (2) that in consolidating several old genera one of the old 

 names and not a new one must be employed for the consolidated 

 group; (3) that when a heterogeneous group is subdivided, its name 

 must be retained for one of the resulting subdivisions; and (4) tliat 

 we are under no obligation to accept the first species of a list as the 

 type of a group for which no type has been selected by the original 

 author, but that we should accept the decision of the first subsequent 

 author who undertakes to select tjqies from the original list in revis- 

 ing it. 



In the following notes only the question of nomenclature is con- 

 sidered, the validity of the sections is left to the specialist in this 

 difficult group. In matters of specific synonymy, I have depended 

 on L. Pfeiffer, Pilsbry and Sterki. 



Isthmia Gray, 1821. The sole example cited is Vertigo pygmaa 

 Drap., which must be regarded as the type. Staarodon Lowe, 1852, 

 and Dexiogyra Stabile, 1864, are synonymous. 



