DIOSTOPORA. 277 
the mouths are raised, with a round oblique plain aperture. 
The finest and largest specimens I have seen were on the 
valves of Pecten ingens, from the islands of Tiree and Coll, 
sent to me by my frierid, the Rev. A. Nicol. 
Genus III. IDMONEA, ZLamourouz. 
Gen. Char. Polypidom calcareous, divided dichotomously, 
erect, celluliferous on one side only; cells tubular, in transverse 
rows, divided into two sets by a medial longitudinal line. 
1. Ipmongea Arttantica, #. Porées. 
Hab. Zetland Seas, Prof. E. Forbes; island of Coll, 
D. L., from the Rev. Mr. Nicol. 
Erect, white, firm, dichotomous; branches spreading 1a- 
terally; the cells tubular, forming a series of transverse 
rows on each side of the coral; the rows are on one side 
alternating with those of the other. Four-tenths of an inch 
in height. This is one of the numerous discoveries of Pro- 
fessor E. Forbes, who has another species from the Mgean 
Sea, somewhat similar to the J, Atlantica ; and in the col- 
lection of Mr. Stokes there is one from Kamtchatka. 
