OF CONCIIOLOGY. 83 



and suggested for them the name u Paludina gibba, Anth." 

 Whether Mr. Anthony, ever published this species or not, I have 

 never been informed ; but the presumption is, in the absence of 

 evidence, that he did not publish the species. At the time I 

 received these shells, which was several years ago, I urged to 

 Mr. McNeil the following objections to Mr. Anthony's opinion 

 as to the " species " and to the use of the name "gibbet." The 

 name (as our nomenclature then stood) was preoccupied by a 

 shell found in France. The shells were apparently a local modi- 

 fication of rufa — an idea that was very forcibly suggested to me 

 by the fact that I had at that early day found a few specimens 

 of Melantho rufa, Ha Id., in the Mohawk River, in which the 

 gibbous phase was developed as an accidental variation, suggest- 

 ing that the species might be, under favorable circumstances, 

 capable of a permanent variation in that direction. The epi- 

 dermis was polished, as in rufa. The apex, where entire, was 

 pink, as in rufa. The interior of the shell also was pink, as in 

 rufa. The embryonic young was pink, and had the glistening 

 polished epidermis of rufa. 



I will now add that the gibbous shells from Mr. McNeil, and 

 also the one figured to illustrate Mr. Currier's species, are all 

 immature — or not adult specimens. In tracing the gibbous shells 

 to maturity I found that the mature shells lost their gibbous 

 character by assuming a more rounded form in the last whorls 

 of the adult, and also by the loss of a considerable portion of the 

 apicial whorls by erosion. In the Mohawk River the gibbous 

 specimens are comparatively rare. They do not exceed one or 

 two per cent, of all the specimens of rufa that may be found. 

 About a dozen such specimens have fallen into my hands in the 

 last ten years. I have barely a single specimen now in my col- 

 lection. This, if the interest of science demands, I am ready to 

 donate to the Conchological Section of the Acad. N. S. 



Since the gibbous phases of one species of the genus Melantho 

 have been the occasion of so much remark, it may not be out of 

 place here also to remark upon the gibbous phases of other spe- 

 cies. Among the shells I had from Grattan, Michigan, through 

 the kindness of Mr. McNeil, were a few specimens which at that 

 time I could not identify with any other species than decisa. In 

 those specimens the gibbous phase was not so marked as in rufa. 

 The deviation from the normal form consisted more in an elon- 

 gation of the shell in the direction of its axis. 



These constitute all the gibbous shells I have ever met with 

 away from localities under my own immediate inspection. For 

 a few years past I have given especial attention to the abnormal 

 forms exhibited by the three species of Melantho found in the Erie 



