750 Transactions of the Society. 



Dentalina communis d'Orbigny, plate XV. fig. 5. D'Orbigny, 

 1826, Ann. Sci. Nat., vii. p. 254, No. 55 ; Jones, Parker, and 

 Brady, Crag Foram. Pal. Boa, 18(56, p. 58.— This rather fine 

 individual, with straight septa, appears to have been still larger, 

 as the last perfect chamber shows the broken base of another. It is 

 smooth and translucent. One specimen and fragments ; black clay. 

 Dentalina communis d'Orbigny, var., plate XV. fig. 6. — 

 Much smaller than the last, but almost identical in other characters. 

 Our figure is from the black clay, but it occurs, though rarely, in 

 both clays ; also at Chelsea. 



Dentalina elegans d'Orbigny, plate XV. fig. 7. D'Orbigny, 

 1846, Foram. Tert. Vienne, p. 45, plate i. figs. 52-6.— An 

 extremely delicate variety, and even neater than d'Orbigny's figure. 

 One specimen ; black clay. 



Dentalina inornata d'Orbigny, plate XV. fig. 8. D'Orbigny, 

 1846, Foram. Tert. Vienne, p. 441, plate i. fig. 50. — The three 

 last chambers of a Dentalina very near to d'Orbigny's figure. 

 From the black clay. 



Dentalina pauperata d'Orbigny, plate XV. fig. 9. D'Orbigny, 

 1846, Foram. Tert. Vienne, p. 46, plate i. figs. 57-8. — Charac- 

 terized by its squat appearance, chambers square-shaped in side 

 view, and regularly even in growth. Two specimens ; from the 

 brown clay. 



Dentalina abnormis Keuss, plate XV fig. 10. — Reuss, 1863, 

 Sitz. k. Ak. Wiss. Wien, xlviii. p. 46, plate ii. fig. 24. — A three- 

 chambered form, found by Eeuss in the " Septarienthon " of 

 Offenbach. Black clay. 



Dentalina aclolphina d'Orbigny, plate XV. fig. 11a, b; 12. 

 D'Orbigny, 1846, Foram. Tert. Vienne, p. 51, plate ii. fig. 18. — 

 This elegant and very common variety appears at first sight to be 

 smooth ; but under the Microscope it shows bases of delicate spines. 

 These are uniformly distributed over the last chambers, but very 

 regularly in two rows around the basal half of each of the other 

 chambers. As these shells have been found by us straight instead 

 of curved, and so becoming very much like the simpler forms, this 

 arrangement of spines helps to fix the variety. A delicate spine, 

 sometimes forked, usually commences the first chamber, and is 

 generally placed on the concave side of the shell. Fig. 116 is a 

 perfect mouth from another individual. Fig. 1 2 is a perfect, but 

 feebly grown specimen. Very common in the black, rare in the 

 brown clay. 



Dentalina spinulosa (Montagu), plate XV. fig. 13. Nautilus 

 spinulosus Montagu, 1808, Test. Brit. Suppl., p. 86, plate xix. 

 fig. 5. Our specimens are like that figured by Sowerby in 

 Wetherell's paper on the ' Hampstead Well' (op. cit.). — An 

 extremely variable form in its markings, which pass from true 



