158 FORAMINIFERA 



aperture circular, complex, formed by numerous incurved 

 lamellae meeting centrally ; chambers not labyrinthic. 

 Recent. 



Genus IDALINA Schlumberger and Munier-Chalmas, 1884 



Plate 18, fig-ure 17; plate 19, figure 17 

 Genoholotype, fiilnculina antiqua d'Orbigny 



Idalina ScHLUMBERGER and Munier-Chalmas, Bull. Soc. Geol. France, 



ser. 3, vol. 12, 1884, p. 629. 

 Biloculiria (part) d'Orbigny, Prod. Pal., vol. 2, 1850, p. 210. 



Test in the microspheric form quinqueloculine, followed by a 

 triloculine, then biloculine series and in the adult with the 

 penultimate chamber showing as a narrow strip at one side near 

 the base and the final chamber making up the remainder of the 

 surface of the test; aperture cribrate but the chambers not 

 labyrinthic. 



Upper Cretaceous. 



Genus PERILOCULINA Munier-Chalmas and 

 Schlumberger, 1885 



Plate 18, figures 18, 19; plate 19, figure 18 



Genoholotype, Per'doculina zitteli Munier-Chalmas and Schlumberger 

 Periloculina Munier-Chalmas and Schlumberger, Bull. Soc. Geol. 

 France, ser. 3, vol. 13, 1885, p. 308. 



Test similar to Idalina, but the last-formed chamber complete- 

 ly involute, the chambers labyrinthic; aperture complex, 

 cribrate. 



Upper Cretaceous. 



Genus LACAZINA Munier-Chalmas, 1882 



Plate 18, figure 20; plate 19, figure 19 

 Genoholotype, Alveolina compressa d'Orbigny 



Lacazina Munier-Chalmas, Bull Soc. Geol. France, ser. 3, vol. 10, 1882, 

 p. 472. 



Test in the young similar to Periloculina, but in the adult 

 compressed into a flattened spheroid, the apertures appearing 

 as a ring of pores near the periphery on the dorsal side. 



Upper Cretaceous. 



