298 FOSSIL SHELLS OF THE CRAG. 



the inside. The deltoid ligamental pit varies much in shape, 

 and cannot be depended upon as a character, some speci- 

 mens having a central elevation dividing the pit into two 

 parts. Nucula ohlonga has nearly twice the number of teeth 

 on one side that it has on the other, whereas in this species 

 they are nearly equal in number. 



Nucula minuta, PL xiv. fig. 6. 



Area minuta, Mont, page 140. 



„ caudata, JJonovaji, Brit. Shells, tab. 78. 



Red crag, Sutton. 



Of this shell I have found but one specimen, which, how- 

 ever, is in good preservation, and is probably identical with 

 the British recent species. It is however rather more trans- 

 verse, the posterior or acuminated side being a little more 

 produced, thereby removing the umbo farther from the centre, 

 but from the examination of only a single specimen I should 

 not venture to regard these distinctions as specific. I found 

 it myself in undisturbed red crag, three feet beneath the super- 

 incumbent sand. 



Nucula pygmcBa. PI. xiv. fig. 7. 



Nucula pygnuEa, Goldfuss, Pet. Tab. 125, fig. 17. 

 „ tenuis, Philippi, page 65, tab. 5, fig. 9. 



corhuloides. Smith, Wern. Mem., viii. t. 2, f. 10, 10*.^ 



Shell transversely ovate, gibbous, smooth, thick, sub-equilateral, one 

 side slightly acuminated, the other rounded, umbo prominent, margin 

 entire. Longitudinal diameter ^ ; transverse diameter ^ of an inch. 



Coralline crag, Ramsholt and Sutton. 



I have given the above as synonymes, presuming all to 

 refer to the same species, although there are some slight dif- 

 ferences which require notice. The crag shell appears to be 

 smaller than any of those quoted, and among fifty specimens 

 that I possess, not one is more than two-thirds the size of the 

 Nucula given me by Mr. Smith, and which was obtained by 

 him in the deposit exposed by the cutting for the Greenock 

 railway. In the description by Philippi, the term " tenuis- 

 sima^'' is used for his shell, a character the present does not 

 merit. I would have adopted Mr. Smith's name, but that I 



1 Figured pi. 2, f. 10. 10*, in a pamphlet entitled " On the last Changes 

 in the relative levels of the Land and Sea in the British Isles," by James 

 Smith, Esq., of Jordan Hill, published in the Memoirs of the Wernerian 

 Nat. Hist. Society, vol. 8. 



