78 HALKYARD, Fossil Foraminifera of the Blue Marl 



layers of matter. Though the figure shows this much, it is 

 necessary to add that the shell-substance between the costse is 

 perforate. The laminated appearance proves that the thicken- 

 ing of the wall and deposition of calcareous matter is not a 

 continuous process, but that there are periods of deposition 

 alternating with resting periods, as in the formation of the 

 woody layers of a tree trunk. 



169. NODOSARIA SCALAR IS (Batsch). 



Nautilus (Orthoceras) scaloris, Batsch, 1791. Conch. Seesandes 



pi. II, 4a, b. 

 Nodosaria scalaris, Brady, 1884, Chall. Rep., vol. IX, p. 510, 



pi. LXIII, figs. 28-31, and LXIV, figs. 16-19. 



This species is extremely rare in these Marls. One speci- 

 men consisting of four chambers was found in material collected 

 in 1902 from sandy veins and pockets in the soft beds exposed 

 between tides at the end of the Quai des Basques. 



170. Nodosaria comata (Batsch). 



Nautilus (Orthoceras^ comatus, Batsch, 1791. Conch. See- 

 sandes, pi. I, fig. 2a, b. 

 Nodosaria comata, Bradv, 1884, Chall. Rep., vol. IX, p. 509, 

 pi. LXIV, figs. 1-5.' 



This may be said to be a costate variety of N. radicula, or 

 a form closely allied to N . scalaris, differing from the last 

 in being of a more robust habit, having the sutures less exca- 

 vated, not possessing a produced neck at the oral extremity, 

 and lacking the elegance of form displayed by well-grown speci- 

 mens of N. scalaris. It differs from N. radicula in being 

 ornamented with longitudinal costse and, instead of being cylin- 

 drical as that species is, N. comata almost invariably has the 

 chambers increasing in diameter from the first to the last. 



It is also very rare at Biarritz, only one specimen is noted 

 which was obtained from a small quantity of marl collected at 

 the top of the cliff about 200 yards south of the villa known 

 as l'Ermitage. 



171. Nodosaria oligotoma, Reuss. 



Nodosaria obligotoma, Reuss, 1872. Geinitz Palseont, vol. XX 

 (1), p. 135, pi. XXXIII, fig. 16. 



A delicate fusiform shell with both ends sharply pointed. 

 It generally consists of four or five segments and is ornamented 



