NO 1177. NO UTH AMERICAN LEPTONACE A— BALL. 895 



This is Montacuta fcrruginosa Verrill. ' 



Ou comparison with authentic specimens of M.ferruginosa Montagu, 

 they appeared to be discrepant. Subsequently a comparison was made 

 wit'li several hundred specimens from thirty-eight different European 

 localities, from Norway to the Mediterranean. None was found to 

 have the characteristics of the Americari shell. The true M. ferrugi- 

 nosn grows to a mucli larger size than any of the Woods Hole speci- 

 mens, and a comparison of the latter with European shells of as nearly 

 the same size as could be found, developed the following differences: 

 The M.ferrnginosa Montagu is longer and more slender, more inflated, 

 its i)osterior end is proportionately longer and more pointed, the beaks 

 more elevated and convex, the dental lamellte more conspicuous, the 

 adductor scars larger and more clean-cut. 



I conclude, therefore, that the two forms are distinct and propose 

 the name of percompressa for the flatfish form from Woods Hole. 



LAS^A RUBRA Montagu. 



A. 32. It is remarkable that this little shell should be abundant at 

 Bermuda, and even in southern California, and unknown on our 

 Atlantic coast. 



TURTONIA MINUTA Fabricius. 



A. 33. In examining the muscular and pallial scars of a large number 

 of American and European specimens I found that there was a certain 

 amount of variation among them. However, none of them showed the 

 extreme discrepancy in size of the pedal scar ls figured by Professor 

 Verrill,^ and it would seem as if his specimen must have been abnor- 

 mal and exceptional. I found the pedal scar large, but never attaining 

 the size of the adductor near it. I also found the range of variation in 

 Alaskan and British specimens quite sufficient to cover the differences 

 which led Professor Verrill to suggest that the British and American 

 shells might belong to distinct species. 



ALIGENA ELEVATA Stimpson. 



A. 35. The genus Aligena H. C. Lea, 1845, from an examination of 

 his types, proves to have been based upon a species of which Montacuta 

 elevata Stimpson is a recent representative. It occurs in the Tertiaries 

 of both Europe and America. Spaniodon Eeuss is probably, and 

 Laubriereia Cossmann certainly, congeneric, as is Kelliopsis Yerrill and 

 Bush. 3 



The species is Montacuta hidentata Gould, 1841, not of Montagu, 1804; 

 Montacuta elevata Stimpson, 1851 , not of Morch, 1875 ; Gyamium elevatum 



'Trans. Conn. Acad., VI, 1884, p. 225, pi. xxx, fig, 13; Proc. U. S. Nat. Mus., XX, 

 1898, p. 783, pi. xc, figs. 7, 8. 

 ^ Am. Journ. Sci., 3d ser.. Ill, 1872, pi. vii, figs. 4, 4a. 

 3 Proc. U. S. Nat. Mus., XX, 1898, p. 784, pi. xciii, figs. 2-4; pi. xciv, figs. 7, 8. 



