NUMMULITES. MOLLUSCA. 19 



N. Pompilius, Lin. Shell suborbicular ; the turns smooth on the back 

 and sides ; the aperture oblong, subcordate ; the umbilicus cover- 

 ed over. Inhabits the Indian seas Bonati. 1. fig. 1, 2. 



A large and beautiful shell of a yellowish colour, banded transversely with red at 

 its posterior part. The outer layer is frequently removed, in order to disclose the 

 fine pearly substance beneath. It is also frequently carved, and shaped into various 

 fantastic forms. Its greatest diameter is about eight inches. 



N. umbilicatus, Lam. Shell suborbicular, umbilicate on both sides ; 

 all the turns visible in either umbilicus ; sides obtusely wrink- 

 led ; aperture rounded, subcordate. Inhabits the Indian seas. 

 Lam. vii. 633. 

 This species is very rare. Its colours are much the same as the N. Pompilius, 



but it does not attain the same size. 



N. crispus, Lin. Shell spiral, with contiguous whorls, and the 

 joints crenated ; aperture semicordate. Very minute. Found on 

 the shores of Great Britain Mont. pi. 18, fig. 5. 



N. calcar, Mont. Shell spiral, smooth, carinated ; joints six, with 

 the partitions elevated and flexuose ; keel entire ; aperture semi- 

 cordate. Minute. Found on shells and corallines on the English 

 coast. Mow*. Test. pi. 15, fig. 4. 



N. depressulus, Mont. Shell spiral, much compressed, with about 

 nine joints, and a small pellucid spot in the centre ; colour white, 

 semipellucid. Very minute. Found on the British shores. 

 Mont. Sup. pi. 18, fig. 9. 



N. crassulus, Mont. Shell spiral, compressed, umbilicated ; joints 

 numerous ; aperture rather oblique ; colour pale-brown. Very 

 minute. Found in England on the Kentish coast. Mont. Test. 

 pi. 18. fig. 2. 



The fossil species of this genus are numerous ; and in Britain have been found 

 in various strata, from the transition limestone and limestone of the old red sand- 

 stone to the more recent formations of chalk marl, green sand, and London clay. 

 Fleming, 229. 



Gen. 12. NUMMULITES, Lam. 



Shell lenticular, attenuated towards the margin ; spire internal, 

 disciform, multilocular, covered over by several tables ; the 

 outer wall of the turns complicated, extending and uniting 

 on each side at the centre of the shell ; cells very numerous, 

 small, alternate, and formed by transverse imperforate septa. 



The Nummulites are very singular animal productions. Their form is lenticular, 

 more or less gibbous in the centre, and circular, presenting on their truncated sur- 

 face eighteen to twenty narrow turns, which departing from the centre seem to run 

 circularly round, and describe a kind of spire. They are all fossil, and have been 

 found in Germany, Switzerland, France, England, Spain, and Egypt. 



Gen. 13. VORTICIALIS, Lam. 



Shell disciform, spiral, multilocular, with contiguous turns, which 

 do not appear externally ; transverse imperforate septa, not 

 extending from the centre to the circumference; aperture 

 marginal. (Fossil.) 



