NATICA (POLINICES) TRISERIATA. 697 



Remarks. — Two distinct shells, differing widely in form and size, have been 

 described under the present name, the one by Dujardin being a Miocene species 

 unknown from the Crag, the other by Wood, which has but little resemblance to 

 it, the affinity of the first being rather with the N. hemiclausa of Sowerby. The 

 difference between the two forms has been recognised by MM. Dollfus and 

 Dautzenberg, Prof. Sacco and others. By the kindness of my friend Prof. Peyrot, 

 of Bordeaux, who has sent me a specimen of Dujardin's shell, I am able to figure 

 a typical example of it which corresponds accurately with that given by its author. 

 Prof. Sacco considers N. varians a variety of the recent British shell N. catena, 

 though he states distinctly it is not the N. varians of Wood. We may take 

 it, I think, that when the specific name varians is mentioned by an English 

 writer, it is Wood's shell and not Dujardin's that is referred to. We have nothing 

 in the Crag exactly agreeing with the original A", varians of the French Miocene. 



Sub-genus POLINICES, Montfort, 1810. 

 Natica (Polinices) triseriata (Say.). Plate LIV, figs. 6, 7. 



1824. Natica triseriata, Say, Joum. Acad. Nat. Sci. Philad., vol. v, p. 209. 



1841—70. Lunatia triseriata, Gould, Kep. Inv. Mass., ed. 1, p. 233, fig. 165, 1841 ; ed. 2, p. 340, 



fig. 610, 1870. 

 1879. Natica triseriata ? S. V. Wood, Mou. Crag Moll., 2nd Suppl., p. 31, pi. iii, fig. 14. 

 1915. Polinices (Euspira) triseriata, Johnson, Bost. Soc. Nat. Hist., Occ. papers, vol. vii, Fauna New 



Engl., No. 13, p. 206. 



Specific Characters. — Shell small, ovate, globose ; whorls 5, the last much the 

 largest, not distinctly compressed below the suture ; oblique lines of growth 

 clearly marked ; spire elevated, more prominent than in the species next 

 described ; suture slight ; mouth rather large, expanded, angulated above, flattened 

 below ; outer lip thin, gently curved ; inner lip forming a fairly wide callus but 

 slightly covering the umbilicus ; umbilicus of moderate size. 



Dimensions. — L. 20 mm. B. 15 mm. 



Distribution. — Recent ; New England coast. 



Fossil : Waltonian Crag : Beaumont, Little Oakley. Butleyan : 

 Butley, probably elsewhere in the Red Crag. 



Remarks. — In his 2nd Supplement Wood figured a specimen which he referred, 

 though with some doubt, to a North American species, N. triseriata, regretting 

 he had not a recent shell with which to compare it. By the kindness of Mr. C. W. 

 Johnson, of the Massachusetts Institute of Technology, I am now able to do so. 

 I have several doubtful examples from the English Crag, one of which I figure 

 with the latter — they seem to belong to the present species ; at any rate the 

 American and verified specimen may be useful hereafter to students. 



American conchologists have adopted the generic term Polinices for this group : 



