416 Mr. H. B. Brady on a 



largely represented in the Miatschkovo rock. Of our Plate, 

 figs. 1 and 2 are from perfect specimens, figs. 3 and 4 from 

 worn and broken ones ; the latter correspond pretty accurately 

 with one of the drawings in the ' Oryctographie.' The size 

 of the specimens also answers to the dimensions given by 

 Fischer. The shell-wall is somewhat thick in comparison 

 with that of many varieties ; and the chambers show more or 

 less tendency to subdivision into chamberlets, but not to the 

 extent to which the same character may be observed in several 

 of the larger members of the genus. 



Ehren berg's figures of Alveolina prisca and A. montipara 

 are sufficiently marked representations of this typical form — 

 the one being very slightly smaller, the other a little larger, 

 than the dimensions appended to the original description. 

 Slight variations in size and proportional contour are of 

 course only individual peculiarities. 



FusuUna constricta (Ehrenberg) . 



Borelis constricta, Ehrenberg, Mikrogeologie, loc. cit. 



Under the above name Ehrenberg figures an oddly shaped 

 FusuUna, somewhat less than 4 milliins. in length, and rather 

 under 3 millims. in diameter at its broadest part, rounded at 

 the ends, and irregularly constricted near the middle. Dr. 

 Carpenter * associates the figure Avith the F. hyperhorea of 

 Salter f ; and Messrs. Parker and Jones % refer it to the same 

 arctic species. It is quite possible that their estimate may be 

 correct ; but there is an alternative view which is worth consi- 

 deration. The specimens described by Mr. Salter are very 

 large, not less than 14 millims. in length ; and the central 

 constriction is gradual and rounded. These appear to be 

 normal (not exceptional) characters in the Fusulince of the 

 Carboniferous Limestone at Depot Point, their arctic locality. 

 Ehrenberg's specimen is a great deal smaller : but that is not 

 all ; the thinning towards the centre is altogether irregular, 

 and it appears much more like the effect of a weathering or 

 wearing of the surface than as a character of the original shell. 

 Nearly all worn specimens of FusuUna show the effects of 

 attrition most near the middle, where the test is thinnest 

 owing to the room occupied by the aperture ; and it seems 

 more probable, all things considered, that F. constricta consti- 

 tutes an intermediate variety of the type, shorter and less 

 fusiform than F. cyUndrica and longer than F. princepsj and 



♦ Introd. p. 305. 



t In ' Belcher s Arctic Voyage,' 1855, vol. ii. p. .380, pi. xxxvi. figs. 1-3. 



X Ann. & Mag. Nat. Hist."' 1872, ser. 4, vol. x. p. 268. 



