200 



CRISTATA.— Three Genera. 



Shell semidiscoidal, spire eccentric. 



Renulites. Shell reniform, flat, sulcated, multilocular; chambers linear, 

 contiguous, curved about a marginal axis, the most distant from the axis the 

 longest. 



A fossil species. 



Cristellaria. Shell semidiscoidal, multilocular; whorls contiguous, 

 simple, progressively enlarging; spire eccentric, sublateral; septa imperforate. 



Microscopic shells, nine species of which are enumerated by Fichtel; — see Ency. Meth. 

 pi. 467, fig. J, a. b. c. 



Orbiculina. Shell subdiscoidal, multilocular; whorls contiguous and 

 compound; spire eccentric; chambers short, very numerous; septa im- 

 perforate. 



O. numismalis, O. angulata, O. uncinata, 



' nummata, Ency. Meth. pi. 468, fig. 1, a. b. c. d. 



SPH^RULATA.— Three Genera. 



Shell globular, spheroidal or oval; whorls of the spire covering, or the 

 chambers united under the envelope. 



Miliola. Shell transverse, ovate globular or elongated, multilocular; 

 the chambers transverse, surrounding the axis, alternately covering one another; 

 aperture very small, situated at the base of the last whorl, either orbicular or 

 oblong. 



A minute shell, one recent species of which is found on fuci, at the island of Corsica. 



Gyrogonites. This genus has been formed from the seed of a species 

 of chara, in a fossil state. 

 A fossil. 



Melonites. Shell subspherical, spire central; whorls contiguous, con- 

 volute, tuniciform; chambers narrow and numerous; septa imperforate. 



Two species. 



