NOTES ON THE CAMBRIDGE. GREENSAND. 489 



the pinched-up back ; this character is very conspicuous in the 

 inner whorl, but becomes gradually less in the later chambers. 



The species was found by Leymerie in the Gault of the Departe- 

 ment de PAube ; but I have not seen it quoted from any other 

 locality. 



Nautllcis dosqualis, Sow. 



Nautilus incequalis, Sow. Min. Conch, pi. lx. lower figs. 

 Nautilus Clementinus (?), Pict. & Camp. Ste. Croix, vol. i. pi. xix. 

 fig. 1-5 (nee D'Orb). 



If the figure and description of M. d'Orbigny's Nautilus clemen- 

 tinus be compared with those of Pictet and Campiche, I think it 

 will be evident that the two are really different species, supposing, 

 of course, that the figures are correct representations of the original 

 specimens. This can only be decided by an inspection of the types, 

 which I have not had an opportunity of making ; it is remarkable, 

 however, that both the figured forms appear to be represented among 

 the Cambridge Nautili. Those agreeing with the N. Clementinus 

 of D'Orbigny are large and somewhat compressed, oblong in cross 

 section, not inflated, but rather flattened near the umbilicus, which 

 is small. Those resembling the figure of Pietet and Campiche are 

 more inflated, and broader in proportion to their length, with a 

 larger umbilicus bordered by a low keel (which, however, is not so 

 marked as in N. expansus) ; the siphuncle is situated close to the 

 inner edge of the chamber. Both forms have numerous close-set 

 chambers, about 16 being visible ; but the latter does not appear to 

 attain so large a size as the true N. Clementinus. 



The smaller and more inflated form certainly appears to exist in 

 the Folkestone Gault, and when obtained thence has, I believe, 

 been usually referred to the N incequalis of Sowerby, with the 

 meagre description and poor figures of which it sufficiently agrees. If, 

 therefore, I am correct in the above surmises, the N. Clementinus of 

 Pictet and Camp, becomes a synonym of N. incequalis, Sow. The 

 inequality of the chambers in the young shell, and the increasing 

 propinquity of the septa being, however, the ordinary mode of 

 growth in the genus, its designation seems rather meaningless. 



Nautilus n. sp. 



Cast oblong, umbilicated, chambers few, only 12 being generally 

 visible, and the last ones being as high as they are wide ; the septa 

 are consequently wide apart, sinuate and bent back near the 

 umbilicus ; siphuncle situated outside the centre and about one third 

 of the distance from the outer edge. 



This is the commonest form of Nautilus among the Cambridge 

 coprolites, but does not seem to agree with any previously described. 

 Casts of the umbilicus seem to indicate that the shell had faint 

 longitudinal striae crossed by the lines of growth. Until, however, 

 the shell has been found and the Nautili of the Gault more 

 thoroughly investigated, it will be safer not to give a name to the 

 above- described casts. 



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