1 26 HALKYARD, Fossil Foraminifera of the Blue Marl 



(The most distinguishing feature of this variety as com- 

 pared with the other Biarritz specimens is its abnormal size and 

 corresponding increase in the development of markings. As 

 Halkyard says that the only specimens were obtained in Gather- 

 ings remarkable for the large size of other species, it would 

 appear to be merely a case of intensive development owing to 

 favourable conditions of life.) 



Genus Rotalia, Lamarck. 

 318. Rotalia soldanii, d'Orbigny. 



Rotalia (Gyroidina), soldanii, d'Orbigny, 1826, Ann. Sci. Nat., 



vol. VII, p. 278, No. 5. 

 Rotalia soldanii, Brady, 1884, Chall. Rep. vol. IX, p. 706, pi. 



CVII, figs. 6-7. 



Frequent. Found in all Gatherings. 



319. Rotalia umbilicata, d'Orbigny. 



Rotalia umbilicata, d'Orbigny, 1840, Mem. Soc. Geol. France. 



ser. I, vol. IV, p. 32, pi. Ill, figs. 4-6. 

 Rotalia soldanii, var. nitida. Ghapman, 1897. Journ. Roy. 



Micr. Soc, 1898, p. 9, pi. II, fig. 2, a-c. 



Rare. My specimens seem to be identical with Rotalina 

 nitida, Reuss, if Chapman's figure of that species is drawn 

 from a typical specimen. I have not been able to see Reuss' 

 original figure, but there is no doubt that d'Orbigny's figure 

 of the chalk species and Chapman's of his specimens from 

 the Folkestone Gault resemble each other closely, and both 

 might have been drawn from specimens in the collections from 

 the Cote des Basques. In this case d'Orbigny's specific 



name would have the preference, he having published his des- 

 cription in 1840. 



Carpenter and Brady referred this form to R. soldanii, 

 d'Orb., and were certainly correct from their point of view, 

 for it must not be forgotten that they were regarding the 

 question somewhat broadly, and with a laudable desire to pre- 

 vent undue multiplication of specific names. When, however, 

 one finds in a series of Gatherings like the present the typical 

 R. soldanii and also its variety R. umbilicata unconnected by 

 intermediate forms and easily distinguishable one from the 

 other, it is convenient to retain their distinctive names. 



(The specimens agree very well with d'Orbignv's original 

 figures (d'O. 1840, C.B.P. p. 32, pi. Ill, figs. 4-6.) The original 

 Reuss figures of Rotalina nitida are too small to be serviceable 



