420 :\Ir. II. B. Brady on a 



Such are tlie general indications afforded by the study of 

 this little group of fossils from the Miatschkovo limestone. 

 The chief thing to be regretted is that so little can be learnt 

 from them with respect to the minute structure of the test. They 

 are all comparatively thick-shelled ; but the finer characters 

 are completely obscured by mineral infiltration, and even the 

 tubulatiou of the walls can scarcely ever be traced. The 

 position of the genus Fusuh'na, whether more nearly related 

 to the Xummuline or the Kotaline types of Foraminifera, is 

 still an occasionally debated point ; and though the subject has 

 been treated by Dr. Carpenter* with much clearness, and the 

 value of the characters pro and con in each case has been 

 stated by him in a way that leaves little to be desired, it is 

 still important that evidence should be obtained as far as 

 possible from each section of the genus. 



In general terms it may be said that, in the perforation 

 of the shelly investment, Fusulina occupies a place ^between 

 the Rotaline and the Nummuline types, wdiether as to the 

 size of the tubuli or their distance apart; and in both of 

 these particulars it approximates more nearly to the former 

 than to the latter group. The absence of double septal 

 lamellaj, and consequently of supplementary skeleton and its 

 attendant canal-system, form irrimd facte evidence against 

 Kummuline afiinity. On the other hand, the usually per- 

 fect bilateral symmetry of form and the position of the aper- 

 ture on the median plane are essentially Nummuline features. 

 Practically, therefore, the decision on the question depends 

 on the amount of significance to be attached to the canal- 

 system as a basis of classification ; and to foiTn a correct esti- 

 mate on this point it is needful to look beyond the genus 

 Nummulina and its immediate allies. 



Amongst the Rotalinje, for example, at least three genera 

 present quite unmistakable evidence of this higher organiza- 

 tion : Rotalia, Calcarina^ and Tinoporus can be shown each 

 of them to have a characteristic system of interseptal passages. 

 The modifications of these three types may be traced in series 

 from their simpler to their more complex forms — that is, from 

 minute varieties, with thin shells and single septal walls, to 

 more massive representatives, having a supplementary skeleton 

 developed to a greater or less degree and furnished with a 

 system of ramifying canals. 



The series comprised in the genus Botalia has, to begin 

 with, a delicate thin-shelled variety [R. nitida, Will.), in- 



* Introd. Foraru. p. 306 ; and Monthly Micr. Joiim., April 1, 1870, 

 p. 182. 



