142 BOOK OF SPECIES. 



NODOSARIA. 



Elongated, straight or slightly arched, sub-conical, 

 nodular; nodules globular, very smooth ; cham- 

 bers formed by transverse septa, perforated in 

 the centre or near the margin. 



N. RADicuLA. Nearly straight, a little taper- 

 ing ; joints transverse ; chambers sub-cylindric, 

 eight or nine. J^. B. W. 13. 27. 



SPIRULA. 



Cylindrical, thin, almost transparent, white or pearl- 

 colour, multilocular, partly twisted into a dis- 

 coidal spiral; whorls distant from one another, 

 the last produced in a straight line; septa 

 transverse, placed at equal distances from each 

 other, externally concave ; siphon lateral, inter- 

 rupted; aperture orbicular. 



S. PERONii. W. Nautilus. 13. 16. 



CRISTELLARIA. 



Shell semi-discoid, multilocular; whorls contiguous, 

 simple, progressively enlarging ; spire eccentric, 

 sub-lateral; septa imperforate. 



C. SQUAMULA. W. 14. 47. 



