110 CARBONIFEROUS AND PERMIAN FORAMINIFERA. 



globular form of Tinoporus." But I must refer the reader to the description itself, which 

 is too long to quote entire ; much of it would apply almost equally to the more complex 

 modifications of the genus Stacheia. 



Lastly, amongst the Nummulinida, if the position assigned to it by Dr. Dawson, 

 Dr. Carpenter, and others be considered as established, appears the largest of all adherent 

 Rhizopods that bone of contention, Eozoon. 



We shall have but little need to refer more particularly to the various types which 

 have been alluded to, except perhaps to Nubecularia, Tinoporus, and Polytrema, but the 

 bare enumeration will have served to show how important a section of Foraminifera the 

 adherent varieties constitute. 



In external form the specimens grouped under the generic name Stacheia present a 

 wide range of variation. In S. marginulinoides the test closely resembles that of a more 

 or less curved, tapering, few -chambered Nodosarine shell; and its originally parasitic 

 condition is assumed, on grounds which will be stated in their proper place, rather than 

 quite positively demonstrated. The closely allied S. pupoides consists also of a simple 

 line of segments, varying in contour according to the nature of the object to which they 

 are adherent plano-convex and outspread if the surface be broad and flat, but concave 

 on the under side and embracing if the object be narrow or cylindrical. On the other 

 hand 8. fusiformis, whilst quite circular in transverse section and tapering symmetrically, 

 almost always retains the evidence of its parasitic habit. In the few-chambered acervu- 

 line variety (S. acervalis) the segments, instead of taking a uniserial line as in 8. pupoides, 

 are irregular in size and piled one iipon another without apparent order. These four 

 varieties all have relatively large chambers, divided in their interior by partial, secondary 

 septa. In Stacheia conyesta a somewhat different condition obtains ; and instead 

 of the large segments there appears a confused mass of minute chamberlets crowded 

 round a foreign body, which is usually of long cylindrical shape. The general con- 

 tour of the organism depends on the nature of the body round which it is built, but 

 it is usually irregularly cylindrical or fusiform, sometimes constricted near the middle. 

 The exterior is granular or nearly smooth, in places exhibiting the sort of reticu- 

 lation that is noticeable on the smooth (non-radiate) varieties of Tinoporus. Lastly, 

 there are the wild-growing, encrusting modifications, named S.polytrematoides, somewhat 

 resembling in habit the porcellanous type Nubecularia, but much more the normally 

 perforate Polytrema, yet differing from both in the minute structure of the shelly 

 investment. 



There is much about the history of the genus Stacheia that is still far from satisfac- 

 torily made out. The specimens are as a rule of very small dimensions, and hitherto the 

 number that have been found has been comparatively limited. Neither the size nor the 

 number would have been any serious obstacle to the complete study of their structure, 

 had they been in the recent state, but, taken in conjunction with age and the effect 

 of fossilization in obliterating minute characters, the want of sufficient material and the 



