from the " Cambridge Greensand." 55 



general appearance this form at first sight resembles Haplo- 

 phragmium acutidorsatum, but it has no chambered structure 

 within the test. Average breadth 1'3 millim. ; thickness 

 *55 millim. 



Concerning the arenaceous forms with a spiral commence- 

 ment of Cretaceous age, it may be noticed that the majority 

 of the earlier-described forms were referred to the genus 

 Lituola. Since the restriction of this genus to labyrinthic 

 forms, the Cretaceous species in most cases now find a place 

 in the genus Haplophragmium, in which the chambers are 

 distinct and simple as distinguished from those with irregular 

 chamberlets or labyrinthula. The labyrinthic forms are more 

 rudimentary from a morphological standpoint, for they indicate 

 that the protoplasmic body gathered up the sand-grains as 

 interstitial particles during the movement and extension of 

 the rhizopod, just as, on the other hand, Astrorhiza and 

 other allied forms in the simplest manner encrust the whole 

 of the dactyloid mass with sand-grains, leaving only the ends 

 free for the protrusion of the pseudopodia. 



As in the fossil Haplostiche, Lituola appears to have the 

 organic interspaces filled with secondary calcite. 



L. placentula occurs with frequency in the Cambridge 

 Greensand of Swaffham. 



Subfamily Trochammininx:. 



Ammodiscus, Reuss [1861]. 



Ammodiscus tenuis, Brady. 



Ammodiscus tenuis, Brady, 1881, Quart. Journ. Micr. Sci. vol. xxi. n. s, 

 p. 51 ; Chapman, 1892, Journ. R. Micr. Soc. p. 326, pi. vi. fig. 12. 



Two well-grown specimens of this species were obtained 

 from Swaffham. 



Family Textulariidae. 



Subfamily Textvlariinje. 



Textularia, Defrance [1824] . 



Textularia minuta, Berthelin. 



Textularia minuta (= T. pygmcea, Reuss), Berthelin, 1880, Mem. Soc. 

 geol. France, ser. 3, vol. i. no. 5, p. 26 ; Chapman, 1892, Journ. R. 

 Micr. Soc. pp. 327, 328, pi. vi. fig. 15. 



This species also occurs in the Gault and Red Chalk. One 

 specimen from Swaffham. 



