WATSON: NOTES ON NOMENCLATURE OF HYGROMIA, HEMCELLA, ETC. 283 



their stead. But Gude and AVoodward state that Petasina Beck (1847) 

 is the correct name to use for this genus, saying: — '■'■ Petasia being- 

 preoccupied was changed to Petasina, which takes of course the 

 same type. Hence Petasina displaces Eticonulus, Reinhardt." But 

 if Beck proposed the new name Petasina to take the place of Petasia 

 because he had discovered that the latter name was preoccupied, we 

 might have expected some note to this effect in the paper in which 

 he first published the name Petasina ; but there is no such note, and 

 nothing at all to indicate that the name was a new one. This suggests 

 the possibility that the name was not intended to be new, but that the 

 // was inserted into Petasia through an error on the part either of Beck 

 or of his printer. And this supposition is rendered still more 

 probable by the fact that in the same short paper Hydrobia is spelt 

 ^^Hygrobia,''' and Montagu is shortened to "Mutg.," instead of to Mtgu. 

 — evident typographical errors. Now if this be the probable origin 

 of the name Petasina, it must be suppressed according to the Inter- 

 national Rules, as will be seen from Opinion 29, which says, in effect, 

 that a name must be suppressed if it is probably a typographical 

 error for another namevvhich is preoccupied. 



There is of course no proof that this view of the origin of the name 

 Petasina h the correct one; the evidence is purely circumstantial. 

 But Gude and Woodward give no proof that their view is correct ; it 

 seems to be a pure assumption. Moreover, as Beck did not say that 

 he proposed the name Petasina as a substitute for Petasia, it can 

 scarcely be maintained that, if it were intended to be a new generic 

 name, he indicated that it must have the same type as Petasia. 

 Therefore Gude's designation of II. edentida Drap. as the type of 

 Petasina in 1911,'^ to which Dr. Pilsbry has kindly drawn my attention, 

 would seem to be valid, \i Petasina is not a typographical error; and 

 in this case the name would have to be used, not in the place of 

 Euconulus, but for the section of Trichia which Gude and Woodward 

 have recently named Petasiella. 



Evidently there is room for a difference of opinion in this case, but 

 probably most zoologists will at least agree that a familiar name in 

 current use ought not to be changed until some sort of proof has 

 been brought forward that the proposed change is not contrary to the 

 International Rules, but in accordance with them. As no such proof 

 has been brought forward in the present instance, it would seem best 

 to continue employing the name Eucouuliis for the genus of which 

 the type species is Helix fulva Miill. 



Oxychilus Fitz., Polita Held, and Hyalinia (Ag.) Charp. 



Since it appears that the International Rules do not require the 



I Proc. Maiac. Soc, vol. ix, p. 362. 



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