SUPPLEMENT. 



ADDITIONAL SPECIES OF MALACOZOA. 



A considerable number of species having occurred, 

 ■while the preceding pages were at press, a supplementary 

 account of them has been found necessary. The Fora- 

 miniferous Cephalopoda have unexpectedly increased, so 

 as to render it expedient to present the characters of their 

 principal families. The additions are owing partly to a 

 last strenuous effort on the part of the author, and 

 partly to the renewed exertions of his friends, espe- 

 cially Mr. Murray and Mr. Gray. 



CLASS L— CEPHALOPODA. Page 20. 

 ORDER III.— CEPHALOPODA FORAaIINIFERA. P. 23,33. 



Family I. — Discorbixa. 



Shell many-celled, with the cells disposed in a single 

 series, curved in a spiral form. Name from the genus 

 Discorbis. Helicdstega of D'Orbigny. 



Genus 1. Polystomella. P. 23. 



2. Polystomella Gullelmince. WilliamincC s Polystomella. 



Shell orbicular-disciform, considerably compressed, 

 with the sides equally convex, bevelled to a thin sub- 



