278 POLYZOA INFUNDIBULATA. 



erect, celluliferous on one side only ; cells tubular, in transverse 

 rows, divided into two sets by a medial longitudinal line. 



1. ID. ATLANTICA, branches roundish, tapered to the point ; 

 cells four in each row, the innermost tubes considerably pro- 

 truded. E. Forbes. 



PLATE XLVIII. FIG. 3, 3. 



Idmonea atlantica, E. Forbes, MSS. 



Hob. Zetland seas, E. Forbes. 



Polypidom neat and erect, of a white colour and firm texture, 

 dichotomous ; the branches spreading laterally, narrow, roundish, 

 tapered to the point ; inferior surface somewhat convex, smooth, 

 pitted or areolar ; superior surface celluliferous, the cells tubular, 

 forming a neat series of transverse rows on each side of the coral, the 

 rows of one side alternating with those of the other, and there are 

 four tubes in each row, the free extremities of the innermost tubes 

 being the longest. Height four-tenths. 



Of the species described by Milne-Edwards, this approaches 

 nearest to the Id. coronopus of Defrance (Mem. p. 23, pi. 12, fig. 3), 

 from which it seems to differ only in the cylindrical form of its 

 branches, that of the Id. coronopus being triangular. 



Idmonea atlantica is one of the numerous discoveries of Professor 

 Edw. Forbes, to whom I am indebted for my specimens. He has 

 another recent species from the ^Egean sea, very nearly related to 

 the atlantica ; and in the collection of Mr. Stokes there is one from 

 Kamschatka. " They appear," says the Professor, " to be very 

 characteristic of great depths ; and when found fossil, as in the 

 chalk, at the junction of the chalk with flints and that without, 

 are always associated with deep sea-forms of Mollusks and Radiata." 



4. PUSTULIPOBA,* Blainville. 



CHARACTER. Polypidom calcareous, erect ; the divisions cy- 

 lindrical ; polype-cells semi-immersed, arranged on all sides, 

 tubular, with more or less prominent apertures. 



1. P. PROBOSCIDEA, slender, branched alternately; tubular 

 cells slightly projecting, alternate, four completing a whorl. 

 E. Forbes. 



* Formed from pustula and iropos, having the pores on pustules. 



