90 HALKYARD, Fossil Foraminifera of the Blue Marl 



specimens or at most two examples in nearly all the Gathering's 

 taken. 



(The species, like many other of those separated by Halk- 

 yard, is hardly worth recordng as apart from its nearest ally 

 C. crepidula.) 



209. Cristellaria lituola, Reuss. 



Cristellaria lituola, Reuss, i845-6,Verstein. Bohm. Kreide, vol. 



II, p. 109, pi. XXIV, fig. 47. 

 C. lituola, Chapman, 1894, Journ. Roy. Micr. Soc, p. 650, pi. 



IX, fig. 14a, b. 



More frequent than the last species but still rare. The 

 species is closely connected with C. gibba, d'Orb, but is more 

 compressed and also the unrolling of the spire is carried out 

 to a greater extent. 



(The specimens agree on the whole very well with Reuss's 

 original figure. It may be regarded as a transition form be- 

 tween C. crepidula and C. gibba.) 



210. Cristellaria robusta, sp. nov. 



PI. VI, fig. 1. 



Test elongate. Segments arranged spirally at first, after- 

 wards in a cylindrical linear series. . Aperture situate at the 

 dorsal extremity of the last segment. Length of well grown 

 specimens, 1.7 mm. 



This is one of the numerous forms which connect Margin- 

 ulina with Cristellaria. The linear series of chambers is circular 

 in section and the aperture is eccentrically placed. So far the 

 species is marginuline. The earlier portion of the shell forms 

 a complete spiral, in fact, it is a small C. rotulata (Lamarck) 

 even to the elevation of the central boss. Its nearest ally in 

 Marginulina is M. ensis. Reuss, which species it closely 

 resembles in the form and segmental arrangement of the 

 linear portion of the test. 



This species can hardly be called rare in the Biarritz Marls 

 but is found, generally speaking, to be confined to the upper 

 half of the beds. 



(There seems very little justification for adding this species 

 to the already vast number of Cristellarians. But for the 

 general rotundity of its cross section, Vaginulina legumen 

 (Linne) covers practically the features on which Halkyard lays 



