86 



THE NAUTILUS. 



The present paper is a companion to that one, dealing with* 

 Gastropoda and one Scaphopod. Forty-six forms are figured 

 in the 118 sketches, on nine plates illustrating the paper. 

 The first twenty-two pages are given to a discussion of the 

 anatomic structures figured, while the last seven are devoted 

 to an arraignment of modern nomenclatorial methods. 



In it interesting to note that of the forty-six species figured, 

 ten bear names that were originally bestowed upon East 

 Atlantic specimens. These species were latfcr recognized 

 as existing in American waters. Experience has taught me 

 to look upon such a distribution with a critical eye, and for 

 that reason I have subjected, in this instance, these ten 

 species to an examination, comparing our splendid collection 

 of East American specimens with the fine lot of material con- 

 tained in the famous Jeffreys Collection of European Mol- 

 lusca now resting in the National Museum, with the follow- 

 ing results: 



Figure 2, ACMAEA TESTUDINALIS Miiller. The American shells 

 average much larger than the European. Some of the 

 specimens actually attain more than double the size of 

 the largest contained in the Jeffreys Collection. There 

 are other essential differences in color pattern, etc.^ 

 enough, I should say, as Acmaeas go, to separate the 

 American from the European form, at least subspeci- 

 fically. "We may therefore call it Acma-ea testudinalid 

 amoena Say, a name that was bestowed upon the Ameri- 

 can species by Say in 1821, Journ. Acad. Nat. Sci. Phila., 

 vol. 2, p. 223. 



Figure 8, CEMORIA NOACHINA Linnaeus. The American shell 

 has long since been recognized as distinct from the Euro- 

 pean, under the name of Puncturella princeps Mighels 

 & Adams, Bost. Journ. Nat. Hist., vol. 4, p. 42, 1842. 



Figure 14, LACUNA VINCTA Montagu. An examination of the 

 East and West Atlantic specimens passing under this 

 name shows that there are sufficient differences in the 

 form of shell, shell texture and finer sculpture to separate 

 the West Atlantic from the East Atlantic form, at least 



