372 APPENDIX. 



Hab. — Bass Strait^ 45 fathoms. 



h. Internodes composed of two-four cells. 



13. Emma, Gray. Dieffenbacli^s New Zealand^ 



Vol. ii. p. 293. 



Cliar. (B.) Cells in pairs or triplets. Opening more 

 or less oblique, subtriangular, partially filled up by a 

 granulated calcareous expansion. A sessile avicularium 

 (not always present) on the outer side, below the level of 

 the opening. 



This genus appears to be a natural one, though very 

 closely alhed to Tricellaria (Fleming) . The more impor- 

 tant points of distinction consist in the conformation of the 

 opening of the cell, and in the position of the avicularium 

 when the latter organ is present. The lower half of what 

 would otherwise be the oval opening of the cell is filled up 

 by a thin plate of calcareous matter, granulated on the 

 surface, and by which the actual opening is rendered more 

 or less subtriangular, the mouth being placed just below 

 the apex of the triangle. The margin of the opening is 

 considerably raised, especially at the oval end, so that the 

 opening appears to be situated in a deep depression. This 

 character of opening, however, occurs also in a triserial 

 species of Cellularia from Algoa Bay. The position of the 

 avicularium entirely below the level of the opening on the 

 outer side of the cell, is the peculiar characteristic of Emma 

 as distinguished from Tricellaria, in which that organ 

 when present is placed on the upper and outer angle as 

 in Cellularia proper, and Scrupocellaria. It is worthy of 

 notice that avicularia may be present on every cell in some 

 specimens, and most usually, whilst in others of equal size 

 there will be none at all apparent. So that the position 

 of these organs in this genus, as well as in Tricellaria, 

 is of more importance systematically than even their 

 existence. 



