410 Transactions of the Society. 



Family VI. CHILOSTOMELLID^). 



Ellipsoidella g.n. 



Among the specimens obtained from the flint were nine, which 

 were at first attributed to Pleurostomella subnodosa* Eeuss, as they 

 agreed, generally, very well with that author's figures of his species, 

 except in respect of the aperture. This was, in our specimens, a 

 crescentic slit situated at the terminal end of the final chamber, 

 the shell on the convex edge of the crescent rising in a slight pro- 

 jection and curving somewhat over the slit. 



The shape of the aperture bore such a striking resemblance to 

 that which is characteristic of Ellipsoidina that it was decided to 

 open some of the specimens, and, on effecting this operation, we 

 found our expectations confirmed by the presence of a central 

 tube exactly similar in structure and position to the axial tube of 

 Ellipsoidina. (PL XI. figs. 1, 2.) 



It thus became evident that our specimens occupied a position 

 intermediate between Pleurostomella and Ellipsoidina, resembling 

 the former genus in the irregular Textularian arrangement of the 

 early chambers, and the latter in the crescentiform aperture, and 

 in the possession of a central column. As Pleurostomella is classed 

 with the Textularidse and Mlipsoidina with the Chilostomellidae, 

 our specimens form a link connecting two families which hitherto 

 have presented hardly any feature in common. 



The genus Pleurostomella was founded by Eeuss for the reception 

 of some fossils from the Westphalian Chalk, and was placed by the 

 author in d'Orbigny's family Stichostegia, which corresponds to 

 some extent with Brady's sub-family Nodosarime, including those 

 genera in which the chambers are arranged in a straight or slightly 

 curved line. It was, however, removed by Brady, and is now by 

 general consent retained in Brady's family Textularidae, to which 

 its affinities certainly belong. It may not be amiss to give a 

 translation of Eeuss' description of his genus from the work 

 already referred to. Eecognising their abnormal character, he 

 created a new sub-family for the reception of the new genus, and 

 proceeds as follows : — 



Pleurostom ellidte. 



" An altogether peculiar group, as yet represented only by the 

 single genus Pleurostomella. It is therefore sufficient to introduce 

 the characteristic features of the genus which so far have sufficed 

 for the whole family. 



Pleurostomella g.n. 



"The first species of this genus, Pleurostomella subnodosa,! had 

 formerly (regarding the irregularity of the chambers as something 

 casual and unimportant) classified with similar varieties of Den- 



* Pleurostomella subnodosa Reuss. Die Foraminiferen der westphiilischen 

 Kreideformation, 1860. Sitz. K. Akad. Wiss. Wien. vol. si. p. 204, pi. viii. fig. 2, a, b. 



