NATICA PUSILLA. 675 



1894. Natiea clausa, Kendall, Journ. Isle of Man Nat. Hist. Soc, vol. xii, p. 417. 



1901. Natiea affinis, Kobelt, Icon, schalentrag. euroj>. Meeresconch., vol. ii, p. 84, pi. liii, figs. 4 — 8. 



1903. Natiea clausa, Lamplugh, Mem. G-eol. Surv. Isle of Man, p. 475. 



Specific Characters. — Shell small, globose, rather thin ; whorls convex, the last 



much the largest, inflated ; spire small and short, with an obtuse and rounded 



apex ; mouth ovate ; outer lip thin, gently and regularly curved, but little 



expanded ; inner lip forming a distinct and semicircular callus, covering the 



.umbilicus; operculum calcareous. 



Dimensions. — L. 12 — 15 mm. B. 10 — 14 mm. 



Distribution. — Recent: Norwegian coast from the Lofoten Islands to the 

 Christiania fiord, Hebrides, West Atlantic, Algiers. 



Fossil: Isle of Man. Waltonian Crag : Beaumont, Little Oakley 

 (very common). Newbournian : Newbourn, Falkenham, Shottisham, Sutton, 

 Felixstowe. Butleyan : Bawdsey, Alderton, Butley, probably elsewhere in the Red 

 Crao;. Icenian : Bramerton. 



Pleistocene : Wexford, Garvel Park, Kyles of Bute. 



Remarks. — The use of the specific term affinis for both the shells here 

 described has led to a certain amount of confusion which for the future should be 

 avoided. It is not always possible to ascertain whether the large northern shell 

 or the smaller one with a more southern range has been referred to. Though 

 comparatively unimportant from a zoological point of view, it may be more 

 convenient for geologists to follow Prof. Sars in using different specific names for 

 them. On the whole the form for which I employ the present one is the more 

 common and more generally diffused in the English Crag. So far as I know 

 neither of them has been definitely reported from that of Belgium. 



Natiea pusilla, Say. Plate LV, figs. 7, 8. 



1822. Natiea pusilla, Say, Journ. Acad. Nat. Sci. Philad , vol. ii, p. 257. 

 1870. Natiea pusilla, Gould and Binney, Inv. Mass., ed. 2, p. 344, fig. 613. 

 1872. Natiea pusilla, S. V. Wood, Mon. Crag Moll., 1st Suppl., pt. i, p. 77, pi. iv, fig. 9. 

 1915. Natiea (Cryptonatica) pusilla, Johnson, Bost. Soc. Nat. Hist., Occ. papers, vol. vii, Faun. New 

 Engl., no. 13, p. 105. 



Specific Characters. — Shell small, sub-globose, strong and solid; whorls 4, the 

 last ventricose, much the largest; spire very short; apex blunt; mouth large in 

 proportion to the size of the shell, semilunar, angulated above, rounded below ; 

 outer lip thin, expanded ; inner lip forming a flattened and semicircular pad, 

 covering the umbilicus or nearly so. 



Dimensions. — L. 4 mm. B. 3*5 mm. 



Distribution. — Recent: North American coast. Rare in New England, common 

 in the south (Johnson). 



Fossil : Coralline Crag : near Orford. Waltonian: Little Oakley. 



