CEPHALOPODA. 319 



Or a few of them may be collected and united as in a pellet, form- 

 ing the Agathistega(I). 



Finally, in the Entomostega(2) the cells are not simple as in the 

 other families, but are subdivided by transverse septa in such away 

 that a section of the shell exhibits a sort of trellis. 



ViRGUlINA, 



Sphehoidina. 



(1) The Agathistega or Milliola of authors, which compose immense banks of 

 II' calcareous stone, in the arrangement of M. D'Orbigny, only form six genera: 



BlLOCUHNA, 



Spirolocuhna, 



Tbilgculiita, 



Articuliita, 



QuiNaTJEtOCUtlBTA, 



Adelosina. 



M- de Blainville assures us that he has ascertained, from observation, that their 

 animal has no tentacula: should this be the case, they are at once greatly removed 

 from the Cephalopoda. 



(2) The Entomostega resemble^ externally, several of the Helicostega. M. 

 D'Orb. divides them into five genera; 



Amphistegtna, 



Heterostegtna, 



Orbiculina, 

 K; Alyeolina, 



Fabtjlaria. 



Those who are desirous of penetrating more deeply into the study of this curious 

 portion of Conchyliology, on which our limits forbid us to expatiate, but which 

 may be useful in the investigation of fossil strata, will find an excellent guide in 

 the Table Method, des Cephalopodes, inserted by M. D'Orbigny in the Ann. des 

 Sc. Nat., 1826, tome VII, p.- 95 and 245, and may profit by the large models con- 

 structed by this able observer. 



