163 Mr. H. J. Carter on Fossil Foraminifera in Scinde, 



tologie et de Geologic Stratigraphiques/ I shall here premise ; 

 that the reader, if inclined to study them, may have no trouble 

 in immediately referring to the same soui'ccs from which I have 

 derived my guide. 



Order III. HELICOSTEGUES. 



Fam. 1. Nautiloid^. 

 Genus Nummulina, D'Orbigny. 

 " Shell free, equilateral, orbicular or discoidal, thick, encrusted, 

 without appendices at the border, formed of a spire embracing, 

 with whorls veiy near together and numerous ; the last always 

 marked in the young animal, but often impossible to be found 

 in the adult. Chambers small, short, near together, veiy nume- 

 rous, the last projecting in the young animal, but indistinct in 

 old individuals ; pierced by an opening, transverse, linear, against 

 the turn of the spire, often concealed in the adult." 



AssiLiNA, D'Orbigny. 



" Shell free, equilateral, orbicular or discoidal, very compressed, 

 formed of a spire embracing only in the young animal. After- 

 wards whorls apparent and without appendices at the border. 

 Chambers small, short, very numei'ous, the last projecting in the 

 young animal, but not so in the adult, each pierced by an open- 

 ing against the turn of the spire." 



" Relations and differences. — The Assilina like the Nummulines 

 have a projecting mouth when young ; but they are distinguished 

 by all the turns of the spire being apparent in the adults instead 

 of being embracing." 



Opekculina, D'Orbigny. 



" Shell free, equilateral, oval or discoidal, very compressed, 

 formed of a spire not embracing, regular, equally apparent on both 

 sides, turns contiguous and increasing very rapidly. Chambers 

 numerous, narrow, the largest projecting beyond all the rest, 

 pierced at all ages by an opening which is visible, triangular, 

 against the turn of the spire." 



" Relations and differences. — It is evident, that by the situation 

 of its opening, this genus comes near to the Assilines ; but it is 

 distinguished from them by its opening being triangular instead 

 of a transverse slit, and by its chambers increasing regularly 

 without becoming narrow towards the opening." 



Alveolina, D'Orbigny. 

 " Shell free, regular, equilateral, round, oblong or elongated 

 in the direction of its axis, not variable in its enlargement, com- 



