REPORT ON" THE FOR AMIN IFER A. 
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tubular form, as was supposed, is generally swollen at the base into a small inflated or 
subglobular chamber, very similar to that seen in certain species of Hyperammina. The 
careful examination of Mr. Kobertson’s mountings has, in point of fact, revealed no 
characters not already provided for in the definition of the genus Hyperammina, and on 
that account the species has been removed to the position it here occupies. 
Fig. 10 . — Hyperammina arborescens, Norman, sp., dredged off Cumbrae. 
а. Two specimens growing attached to a stone ; magnified 20 diameters. 
б. Primordial chamber of another specimen ; magnified 20 diameters. 
The distinctive features of Hyperammina arborescens are the extreme tenuity of the 
tube, and its nearly uniform diameter throughout, the erect habit, and the dichotomous 
branching of the stem. These characters, together with its reddish-brown colour and 
comparatively smooth exterior, are sufficient to separate it from Hyperammina ramosa 
and Hyperammina vagans, the only species with which it is likely to be confounded. 
