I io HALKYARD, Fossil Foraminifera of the Blue Marl 



Apart from the external form, being ovate and not circular, 

 this species shows all the characteristics of L. brugesii, Schlum- 

 berger. The form of the chambers, the shell-wall, and the ex- 

 ternal appearance and structure of the thickened central portion 

 are absolutely identical. The young shell is spicular or fusi- 

 form, the long axis being sometimes five times as long as the 

 shorter one, whilst in the most highly developed test I have 

 met with (fig. io) the proportion is less than two to one. This 

 seems to show that the cells on the long axis are at first 

 developed more rapidly than the lateral ones, but, after a certain 

 stage is reached, their increase is arrested and the lateral cham- 

 bers gain the ascendency, so that it is quite possible that in 

 time a discoidal shell like Schlumberger's species might be pro- 

 duced. 



This species is not common, but I have collected from 

 eight samples of the Blue Marl, 30 or 35 specimens. 



(Apart from Halkyard's efforts to bring the description of 

 this species within the definitions of Linderina the foregoing 

 remarks present nearly all that can be said for this very curious 

 form. Viewed from the superior surface, both species of Halk- 

 yardia might readily be mistaken for Cymbalopora poeyi 

 (d'Orb.) of the depressed type; only when the under surface 

 is viewed does the secondary deposit in the umbilical recess 

 give the clue to its distinctive structure.) 



266. [Halkyardia minima, (Liebus.)] 



[Cymbalopora radiata, Hagenow, var. minima, Liebus, 191 1, 

 Sitzb. k. Akad. Wiss. Wien. Math. nat. Kl. vol. CXX, 

 Abth. 1, 191 1, p. 952, pi. Ill, fig. 7.] 



266A. Linderina chapmani, sp. nov. 



Pi. VI, figs. 8, 9. 



Test conical, with rounded apex, formed of concentric 

 rows of wedge-shaped chambers. Centre of hollow cone filled 

 up by prolongations of the inferior walls of the cells. The 

 superior surface of the test thickened by the prolongation of 

 the. superior chambers-walls. Diam..6 mm. Height .3 mm. 



This very beautiful species shows clearly by tne form and 

 arrangement of its chambers its relationship to Cymbalopora; it 

 is however more regular in structure and of a higher type. A 

 vertical section (fig. 9, pi. VI) shows plainly by the varying 



