Groaj) of Rassian Fuisulinse. 415 



from the elongate fusiform contour of the type {F. cylindrica) 

 to a compressed lenticular form having the general aspect of 

 a Nummulite. 



The specimen of Carboniferous Limestone to which I have 

 referred was a whitish-grey mass, granular and friable in 

 some parts, more compact in others, and almost entirely com- 

 posed of fossils of small size. A piece, the size of a walnut 

 or somewhat less, was disintegrated by crushing and then 

 washed. Many specimens were doubtless broken in the pro- 

 cess, but no gentler treatment was of any avail. As they 

 exist in the rock, a considerable proportion of the organic 

 remains are already more or less in fragments, and the sur- 

 faces of most of them are water worn ; notwithstanding which 

 a good number, perhaps from a hundred to two hundred, 

 remained in very fair condition for examination. A few of 

 the more characteristic of these are represented in PL XVIII. 

 They have been carefully drawn by Mr. Hollick from the 

 objects themselves, and give a fair idea of the whole. Many 

 additional intermediate forms might have been taken from 

 the collection, had more extended illustration been needful. 

 When it is considered that this series of figures was drawn 

 from a few specimens out of the many that existed in a very 

 small fragment of material, it will be evident that the mass 

 of the deposit, if properly examined, would furnish any num- 

 ber of gradational links between the two extremes of form. 

 The only notable break in the series, as represented in the 

 Plate, is between the normal fusiform variety (figs. 1-4) and 

 the elliptical modification (fig. 5) ; but amongst the broken 

 specimens are fragments that show that transition forms 

 do exist, and that there is no gap that might not readily be 

 filled by the examination of a larger quantity of material. 



As a matter of convenience, many of the trivial names in 

 the foregoing list may be employed with propriety for the 

 salient forms of the group ; but it is to be understood that 

 such names have only varietal significance, and that no truly 

 specific or hereditary distinctness can be claimed for the suc- 

 cessive modifications of so com2)act a series. I propose to 

 notice these salient varieties in order, commencing with the 

 recognized type, Fusulina cylindrica. 



Fusulina cylindrica^ Fischer. PI. XVIII. figs. 1-4. 



Fusulina cylindrica, Fischer, Bull. Soc. Imp. des Nat. Moscou, he. cit. 



dcpressa, id. ibid. 



Alveolina prisca, Ehrenberg, Mikrogeologie, loc. cit. 

 montipara, id. ibid. 



The typical form of Fusulina, as delineated by Fischer, is 



