44 HALKYARD, Fossil Foraminifera of the Blue Marl 



increase in length of the chambers, so I have added a dotted 

 line in the drawing' to show how far these features sometimes 

 go. Such specimens however are generally very small and 

 weak, and perhaps it would not be out of place to view this 

 species as a weak starved form of V . tricarinata. However 

 this may be it must be noted that no passage forms to fill up the 

 gap have been found in the collections now under description. 



(This is a very distinctive little variety of V . tricarinata 

 d'Orb. It is worthy of note merely on account of the excessive 

 concavity of the three faces of the shell; a slight degree of 

 concavity is a normal variation of the genus. It is a minute 

 hyaline isomorph of V. variabilis Brady. (Chall. Rep., 1884, 

 p. 385, pi. XLVII, figs. 21-24.) ) 



76. Verneuiltna triquetra (Minister.) 



Textularia triquetra, Munster, 1838, Roemer, Neues, Jahrb. 



fiir Min., etc., p. 384, pi. Ill, fig. 19. 

 Verneuilina triquetra, Brady, 1884, Chall. Rep,, p. 383, pi. 



XLVII, figs. 18-20. 



Extremely rare, only one small but typical specimen found 

 in the large amount of material examined. 



yy. [Uvigerina selseyensis, Heron-Allen & Earland.] 

 \Uvigerina selseyensis, Heron-Allen & Earland, 1908, etc., 

 S.B. 1909, p.~437> pl- XVIII, figs. 1-3.] 



Genus Tritaxia, Reuss. 



77A. Tritaxia dehiscens, sp. nov. 



PI. Ill, fig. 8. 



Test vitreous, short, early portion tapering, nearly circular, 

 tri-serial, afterwards becoming triangular and uniserial. 

 Hinder margins of chambers projected outwards from sutures 

 so as to leave them a free angular edge. Aperture consisting 

 of a short produced neck with a phialine lip situated at the 

 extremity of the final chamber. Length .35mm. 



The characteristic of the shell which has earned for it its 

 specific name is generally carried out to such an extent as to 

 form a deep cavity on one of the lateral faces of the shell at 

 the base of the last chamber. This little shell is closely allied 

 to Brady's Tritaxia lepida and may be nothing more than a 

 weak or local variety of it. The typical form however is not 

 found at Biarritz, and the present one is rare. The earlier 



