332 On the Genera Webbina and Vitriwebbina. 



resembles an attached Polymorphina, very like the figure of 

 P. concava figured by Williamson * and also like the first 

 segment of the Bamulina cervtcorm's of the Gault f. With 

 regard to this latter it appears highly probable that the 

 attached Ramidinm and the Vitriwehhince are closely related. 



Fig. 3 is a sketch of a specimen of Vitriwebbina Icevis 

 (Sollas) in which the primordial septation is very distinct. 

 This specimen was found attached to a shell-fragment from the 

 " Chalk detritus " of Charing, Kent, and probably of Chalk- 

 marl age. It was substituted for a Gault specimen during 

 the writing of this paper on account of the distinctness of the 

 septate commencement, although many of the Gault specimens 

 are nearly equally good. 



Fig. 4 is a vertical section taken through two of the 

 chambers of a Gault specimen of Vitriicebbina tuberculata, 

 (Sollas) . Here the tubulation of the shell-wall is clearly seen, 



Fig. 4. 



Vertical section of the test of Vitriwebbina tuberculata (Sollas). x 30. 



as well as the superficial tuberculations of clear shell- 

 substance. 



In recapitulation, an attempt has been made to show that: — 



1. Webbina^ as a genus, being originally ill-defined, it is 

 necessary to follow the definition of the first authorities who 

 placed the genus upon a substantial basis, which authors are 

 Jones, Parker, and Brady, 1866. 



2. Those examples of adherent Foraminiferawdiich resemble 

 Webbina externally, but which exhibit a tubulate shell-wall, 

 should be retained in the genus Vitriwebbina. 



* Williamson, W. C, " On the Recent Foraminifera of Great Britain," 

 Ray Society, London, 1858, pi. vi. fig. 151. 

 t Geol. Mag. viii. 1892, p. 54, pi. ii. fig. 5. 



