NATICA (LUNATIA) ALDERI. 687 



Specific Character's. — Shell large, solid, elliptical, slightly oblique; whorls 

 5 or 0, the last strongly ventricose, very largo in proportion to the spire, the 

 upper ones but little convex ; marked transversely by obscure spiral lines, longi- 

 tudinally by numerous inconspicuous lines of growth, and towards the mouth and 

 the umbilicus by irregular spiral foldings which enter the latter; spire depressed, 

 very short, about one-twelfth the total length, projecting but little beyond the 

 body-whorl ; mouth large, wide, semilunar, projecting below, angulate above, 

 four-fifths the length of the shell; outer lip gently rounded, incurved; inner lip 

 spread over the columella, thickened below the upper lip and in the umbilical 

 region ; umbilicus deep, open, fairly large. 



Dimensions. — L. 55 mm. B. 55 mm. 



Distribution. — ? Known living. 



Fossil: St. Erth. Coralline Crag: Sutton. Red Crag: 

 Waltonian to Butleyan horizons, jiassim. Icenian : doubtful. Scaldisien, 

 Poederlien : Belgium, Holland, Iceland Crag. 



Remarks. — This tine and beautiful shell, which is much larger than any other 

 of the Crag Naticas, seems to be confined as far as our present information goes 

 to the Pliocene deposits of the Anglo-Belgian basin and to St. Erth. I have 

 found it to be very common at Walton and Oakley, and it has been reported from 

 every horizon of the Red and Coralline Crags. Considerable doubt attaches in 

 Mr. Bell's opinion, however, to references from the Icenian of Easton Bavent. 



N. catenoides was originally identified by Nyst with an Eocene species described 

 by Sowerby as X. glaucinoides ; but recognising this to be a mistake he afterwards 

 called it jV. Soiverbyi, finally adopting Wood's name (op. cit.), by which it has been 

 known of late years, it seems to be very near to the American species N. heros 

 of Say. 



Natica (Lunatia) Alderi (Donovan). Plate LV, figs 4 — 6. 



1800. Nerifa nitida, Donovan, Brit. Shells, vol. iv, pi. cxliv. 



1836. Natica intermedia, Philippi, Enum. Moll. Sic, vol. i, p. 163, pi. ix, fig. 11. 



1838. Natica Alderi, Forbes, Malac. Monens., p. 31, pi. ii, tigs. 6, 7. 



1853. Natica nitida, Forbes and Hanley, Brit. Moll., vol. iii, p. 330, pi. e, figs. 2—4. 



1859. Natica nitida, G. B. Sowerby, 111. Ind. Brit. Shells, pi. xvi, fig. 16. 



1865. Natica nitida, Rose, Geol. Mag., vol. ii, p. 11. 



1867—71. Natica Alderi and vars., Jeffreys, Brit. Conch., vol. iv, p. 224, 1867; vol. v, p. 215, pi. lxxviii, 



fig. 5, 1869; in Prestwich, Quart. Journ. Geol. Soc, vol. xxvii, p. 489, 1871. 

 1870. Natica Alderi, Wood and Harmer, Rep. Brit. Assoc. (Liverpool), p. 90. 

 1871—93. Natica Alderi, A. Bell, Aim. Mag. Nat. Hist. [4], vol. vii, p. 359 ; vol. viii, p. 50, 1871 ; 



Rep. Brit. Assoc. (Leeds), pp. 417,420, 1890; Rep. Yorks. Phil. Soc, p. 63, 1892 ; Proc Roy.Phys. 



Soc Edin., vol. xii, p. 22, 1893. 

 1872. Natica Alderi, S. V. Wood, Mon. Crag Moll., 1st Suppl., pt. i, p. 74, pi. vii, fig. 27. 

 1873—6. Natica Alderi, Seguenza, Boll. R. Coin. Geol. Ital., vol. iv, p. 352, no. 258, 1873 ; vol. v, 



p, 280, no. 103, 1874 ; N. intermedia, vol. vii, p. 12, no. 494, 1876. 



