672 PLIOCENE MOLLTTSCA. 



Casterlien, Scaldisien : Belgium. 



Remarks. — Originally Wood regarded this form as a variety of F. sulcatus, but 

 in bis first Supplement he considered it sufficiently distinct to lie considered of 

 specific rank. Jeffreys identified it with a recent Japanese shell, F. japonieus, a 

 name which was adopted on his authority for the Crag shell by the Messrs. Bell 

 and by the late CI. Reid. I have tried to procure a specimen of the former, but 

 Prof. Yabe informs me there are none to be obtained either from dealers or from 

 the public museums in that country. Prof. Sacco regarded them as distinct forms, 

 as did Wood, who had the advantage of comparing one of his Crag specimens with 

 a recent example from Japan. 



Genu* NATICA, Adanson, 1757. 



The genus Natica is well represented in the English Pliocene, especially in the 

 Waltonian division of the Red Crag. Originally proposed by Adanson for a 

 number of closely allied forms, it has been divided of late years into several sub- 

 genera, the principal division being between those having a calcareous and those 

 with a corneous operculum. The former term has been for some time confined to 

 a group of which A T . affinis was taken as the type, the sub-generic term Nacca 

 being adopted for shells having a subcentral umbilical ridge, as in the Miocene and 

 Mediterranean species N. millepunctata. The use of Nacca has now been dis- 

 continued by some of our best authorities, N. millepunctata and its allies being- 

 included in the genus Natica, sensu stricto. 



Another group of the Crag species — those with a non-calcareous operculum — 

 has been known under the generic or sub-generic names of Naticina, Guilding 

 (1834), or Lunatia, Gray (1847), the former mainly by southern, the latter by 

 northern Conchologists, and by the Conchological Society of England in their 

 well-known list. Recently Naticina has been dropped by Dautzenberg, Cossmann 

 and other writers, most of the Crag forms hitherto comprised under that name 

 being associated under the sub-generic term Lunatia, with /,. catena as the type. 

 A few Crag species are grouped with Polinices, more largely used in America, 

 confined by P. Fischer to oval and elongated shells having the umbilicus closed by 

 the funicular callosity. 



Natica clausa, Broderip and Sowerbv. Plate LVI, fio-s. 1 — 5. 



1829. Natica clausa, Broderip and Sowerbv, Zool. Journ., No. 4, p. 372. 

 1839. Natica clausa, Gray in Beechey's Voy., p. 136, pi. xxxiv, fig. 3; pi. xxxvii, fig. 6. 

 1842—48. Natica clausa, S. V. Wood, Ann. Mag. Nat. Hist. [1], vol. ix, p. 529, 1842; Mon. Crag 

 Moll, pt. i, p. 147, pi. xvi, fig. 2, 1848, 



