THE NAUTILUS. 53 



likely to occur elsewhere, as the Unionidae are not the worst of 

 travellers. I once found a number of Anodonta Benedicti, which 

 had been thrown ashore by the waves on Onondaga lake, raising 

 themselves on edge and working their way to the water. Can any 

 one point out an invariable feature distinguishing Unio radiatus 

 Sind luteolus ? The distinctions do very well for some, but others 

 seem a good deal mixed. Has not every collector some which he 

 has not named ? 



Shells are not abundant in Colorado, and I took pleasure in show- 

 ing the actions of Helix Cooperi W. G. B. to some there who had 

 never seen a snail. This snail is abundant in "Williams' Canon, 

 near Manitou, but I found it nowhere else, perhaps for want of time. 

 In Cheyenne Canon I collected some very small snails, which I 

 unfortunately lost before identification. Conditions there are sel- 

 dom favorable but something might be done by a zealous naturalist. 

 For myself I confess that other things proved more attractive for 

 the time. In the East, rocks are better collecting grounds, which 

 reminds me how greatly Helix albolabris, on rocky islands, differs 

 from the same shell in more fertile lands. 



A NOTE ON MR. PILSBRY'S " ARTICLE IV.' 



BY T. D. A. COCKERELL, INSTITUTE OF JAMAICA, 

 KINGSTON, JAMAICA. 



It is very unfortunate that so much discussion should seem nec- 

 essary about Limacella or Phllomycus, but I am obliged to add still 

 a few remarks to remove what seems to be a slight misunderstanding. 

 (1) Limacella Brard. My slug notes are not just now at hand, but 

 I think I may safely assert that when Limacella was proposed in 

 1815, the Limax of modern authors was not specially provided with 

 a name. The Linnean lAmax included Avion, Limax, Agriolimax 

 and even an Eolis. The first mentioned species in the Linnean 

 Limax is what we now call an Avion {A. ater). Brard's first Lima- 

 cella, I believe was Limax inaximus of modern authors. Thus, if we 

 were to adopt a very strict rule of priority, Ave might write as fol- 

 lows : 



Limax Linn. (^Arion Fer.') 

 Limacella Brard (=Limax Aucit.~) 



