﻿TROCHAMMINA. — VALVULINA. 



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Trochammina filum {Schmid). PI. Ill, fig. 16. 



Serpula filum, Schmid, 1867. Neues Jahrb. fur Min., Jahrg. 1867, p. 583, pi. vi, 



fig. 48. 



Involutina vermiformis, Brady, 1869. Report Brit. Assoc., Exeter Meeting, p. 382. 

 Trochammina filum, Jones, Parker, and Kirkby, 1869. Ann. and Mag. Nat. Hist., 



ser. 4, vol. iv, p. 389. 



Characters. — Test free ; consisting of a long tube of gradually increasing diameter, 

 irregularly bent, and often partially coiled at its commencement. Aperture formed by 

 the open unconstricted wider end of the tube. 



There can be no doubt, as Messrs. Jones, Parker, and Kirkby have demonstrated 

 {Joe. cit.), that the little vermiform Permian fossil figured by Dr. E. E. Schmid is an 

 uncoiled variety of Trochammina. It differs considerably from the crozier-shaped Car- 

 boniferous form, Tr. centrifuga, in its general contour and mode of growth. In its very 

 earliest portion Trochammina filum, if not entirely uncoiled, is confused rather than 

 helicoid or spiral, and the linear portion of the test is irregularly twisted, and uneven in 

 diameter. Its relationship seems to be rather with Trochammina pusitta than with the 

 more regular Tr. incerta. The drawing, PI. Ill, fig. 16, has been reproduced from 

 Dr. Schmid's figure. 



Distribution. — Although in the examination of Carboniferous material, minute 

 tubular organisms bearing a resemblance to this species often present themselves, I have 

 never, except perhaps from a single habitat (near Skipton, Yorkshire), met specimens 

 that could without cavil be assigned to it ; nor have I any record of its occurrence 

 in the Permian rocks beyond Dr. Schmid's locality, the Zechstein of Selters in the 

 Wetterau, Germany. 



Genus, Valvdlina, d'Orbigny. 



Valvulina, d'Orbigny, Parker and Jones, Seguenza, Carpenter, Brady, Robertson. 

 Tetrataxis, Ehrenberg. 

 Textilaria (in part), Ehrenberg. 

 Rotalina (in part), Williamson, Parfitt. 



General characters. —Test free or adherent, spiral ; trochoid, turbinoid, plano-convex 

 or (in Clavuline varieties) sub-cylindrical ; chambers arranged in a more or less regular 

 spire, sometimes terminating in a single rectilinear series. Aperture (normally) in the 



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