108 CARBONIFEROUS AND PERMIAN FORAMINIFERA. 



they form together so natural a series, that I have had but little hesitation in associating 

 them provisionally under a single generic term, and have employed for their distinction 

 the name of my friend and collaborateur Dr. Guido Stache, of Vienna. 



A brief survey of the present extent of our knowledge of parasitic Foraminifera in 

 general may help to a right appreciation of the characters of those now to be described ; 

 indeed, all the accessory assistance which can be obtained is needed for the proper 

 reading of the obscure, often nearly obliterated, features of these very early fossil 

 rnicrozoa. 



Amongst the porcellanous IMPERFORATA (family Miliolida of Carpenter, Parker, and 

 Jones) the genera Dactylopora? Acicularia, and Nubecularia 1 are, as a rule, parasitic. 

 The two former are elongate, typically cylindrical forms with more or less regular plan of 

 growth. Nubeatlaria, on the other hand, is a polymorphic type which was long regarded 

 as a zoophyte from its encrusting habit. It occasionally shows a tendency to assume a 

 spiral form, but in reality conforms to no definite plan. It spreads over the stones or 

 shells upon which it grows, and adapts itself to their contour, sometimes producing a 

 single layer of misshapen chambers, sometimes an irregular acervuline mass, and in these 

 characters bears considerable resemblance to some of the Carboniferous specimens. 



The genus Squamulina of Max Schultze is assigned by both Carpenter and Reuss to 

 the porcellanous Imperforata, but the researches of Mr. Carter 3 indicate that its 

 proper place may be in the arenaceous series. According to Max Schultze's diagnosis it 

 consists essentially of a plano-convex test adherent by its flat surface and with a single 

 wide orifice on the convex side. In one species described by Mr. Carter the normal 

 lenticular form is supplemented by a tall columnar growth. The shell is calcareous and 

 opaque, and, in some of its varieties at least, largely built up of siliceous sand and sponge 

 spicules. 



Passing to the arenaceous IMPERFORATA (family Lituolida), the genera Trochammina, 

 Lituola, and Valvulina have each their parasitic representatives, and to these must be added 

 the more recently described Polyphragma of von Reuss. 



The typical Trochammina squamata is itself an outspread trochoid and probably adherent 

 form, but the better known attached varieties are those of simpler character to which the 

 sub-generic term Wellnna is applied. They consist of simple, circular or oval, convex 

 tests, subarenaceous in texture, but having a smooth surface, growing either singly or 

 in irregular lines over the broad surface of stones or shells. These oval tent-like segments 



1 Dr. Giimbel, in his memoir "Die sogenannten Nulliporen," 2ter Theil, ' Abhandl. k. bayer. Akad. 

 der \V.,' II Cl., vol. xi, pt. 1, subdivides Dactylopora into five generic groups, Haploporella, Dactylopo- 

 rella, Thyrsoporella, Gyroporella, and Uteria, but this does not sufficiently affect our present purpose to 

 need consideration here. 



2 Prof. Reuss does not appear to have been conversant with the genus Nubecularia, for he associates 

 it with Webbina and Placopsilina, and places all together amongst the arenaceous Imperforata. 



3 ' Ann. and Mag. Nat. Hist.,' ser. iv, vol. v, p. 309, et seq. 



