Recent and Fossil Foraminifera. 413 



Both of these depart from the original definition of the genus in 

 the fact that the early chambers are visible instead of being 

 entirely enclosed by the final chamber as in the type. Ellipsoidina 

 suhnodosa, in fact, to all external appearance is a moniliform 

 Nodosaria, while Ellipsoidina exponens resembles a Glanduline 

 Nodosaria. 



Mr. Guppy in his description of E. suhnodosa recognises the 

 close relationship of his species to Pleurostomella, and he again 

 draws attention to this in a later paper,* in which he attempts 

 to trace the phylogeny of the Foraminifera, and places the genus 

 Ellipsoidina next to Pleurostomella in order of divergence from a 

 central stem. In his original description of E. suhnodosa he re- 

 marks, " Notwithstanding the resemblance in shape to a Nodosaria, 

 this may generally be distinguished by its more regularly 

 cylindrical shape, the separation between the chambers being less 

 strongly marked than in most Nodosariae. The aperture and 

 interior structure are more distinct marks of difference. The 

 species represents a close approach to Pleurostomella ; but the 

 aperture is not situated in a depression as it is in that genus, it is 

 terminal or nearly so. Further in our new species the segments 

 rarely show a tendency to alternate as they do in Pleurostomella, 

 though it is to be observed that in one or two specimens there is 

 an indication of such a tendency near the apex.f The aperture 

 resembles that of Ellipsoidina cllipsoides as represented by Brady's 

 figure (Quart. Journ. Geol. Soc. 1888, vol. xliv. pi. i. fig. 1). Some 

 specimens of Pleurostomella suhnodosa come very close ; see for 

 instance the figures given by Burrows, Sherborn and Bailey 

 (Journ. R. Micr. Soc. 1890, pi. viii. figs. 27-30)." 



This reference to the figures in Messrs. Burrows, Sherborn 

 and Bailey's paper, on " The Foraminifera of the Red Chalk of 

 Yorkshire, Norfolk and Lincolnshire," is of great interest, as we 

 had already noted the resemblance of their figures to our specimens 

 before reading Mr. Guppy's paper. We think there can be no 

 doubt that the specimens from the Red Chalk should be referred 

 to our type, and not to Pleurostomella nodosa Reuss ; and it is not 

 unlikely that an examination of the specimens of P. suh?wdosa 

 in collections would lead to the discovery of other instances in 

 which our type has been incorrectly identified as Pleurostomella 

 suhnodosa. 



This has in effect occurred in one instance at least in which 

 sufficient details have been recorded to identify the specimens 

 beyond doubt with our type. Boissel and Holzapfel, in their 



* " Observations on some of the Foraminifera of the Oceanic Rocks of 

 Trinidad," Proc. Victoria Institute of Trinidad, 1903, vol. ii. pt. i. p. 15. 



t By the courtesy of Mr. Guppy, we have received a good many specimens of 

 E. suhnodosa, but none of them show any sign of a departure from the moniliform 

 plan of growth either externally or when cut in section. 



