280 MESSRS. B. HERON-ALLEN AND A. EARLAND ON THE 



310. Nonionina orbicularis, Brady. 



Nonionina orbicularis, Brady, 1881, HNPE. p. 105, pi. ii. fig. 5 a, b. 

 Brady, 1884, FC. p. 727, pi. cix. figs. 20, 21. 



1 Station. 



One specimen, characterized by a deposit of granular shell-matter over the earlier 

 chambers of the last convolution in the neighbourhood of the aperture. 



311. Nonionina asterizans (Fichtel & Moll). 



Nautilus asterizans, Fichtel & Moll, 1798, TM. p. 37, pi. iii. figs. e-h. 



Nonionina asterizans, Heron-Allen & Earland, 1913, CI. p. 143, pi. xiii. figs. 12, 13. 



8 Stations. 



Scantily distributed, frequent at some Stns., notably at Stn. 4, where the best examples 

 occur. Very little variation except in the depth of the sutural lines. 



312. Nonionina stelligera, d'Orbigny. (Plate 43. figs. 8-10.) 



Nonionina stelligera, d'Orbigny, 1839, FIC. p. 128, pi. iii. figs. 1, 2. 

 Brady, 1884, FC. p. 728, pi. cix. figs. 3-5. 



3 Stations. 



Very rare, the best and most typical specimens at Stn. 10. 



N. stelligera is a very distinctive form of the N. depressula group, characterized by 

 inflated chambers due to the depressed sutural lines. The umbilical portion is clearly 

 marked out by a stellate process radiating down each sutural depression, sometimes 

 almost to the marginal edge. This stellate process is in its highest development almost 

 a secondary series of chambers, due to the partial overlapping of its predecessor by each 

 successive chamber in the convolution. Occasionally this overlapping " star," instead 

 of being a hollow chamberlet, is a solid mass of shell-substance, in which case we get a 

 solid radiating stud or a stellate limbation. 



Far commoner than the true N. stelligera is a form which closely resembles it 

 in superficial appearance, i. e. with swollen chambers and sunken sutural lines, witli 

 radiating stellate ornament, but the ornament in this case is merely superficial and 

 masks rudimentary retral processes. We have separated this form under Polyslomella 

 faba (F. & M.). 



1 



313. Nonionina boueana, d'Orbismv. 



Nonionina boueana, d'Orbigny, 1846, FFV. p. 108, pi. v. figs. 11, 12. 

 Brady, 1884, FC. p. 729, pi. cix. figs. 12, 13. 



7 Stations. 



Very rare and far from typical ; the only really good examples at Stn. 6. 



314. Nonionina scapha (Fichtel & Moll). 



Nautilus scapha, Fichtel & Moll, 1798, TM. p. 105, pi. xix. figs. d-f. 

 Aouiunina scapha, Brady, 1884, FC. p. 730, pi. cix. figs. 14, 15, 10 (?). 



