CEPHALOPODA. 53 
Navtitus zic-zac. Nyst. 1843. Bull. Soc. Géol. de France, vol. xiv, p. 452. 
_ _— — 1843. Desc. des Coq. foss. &c. des Terr. tert. dela Belgique, 
p- 644, pl. 46, fig. 4. 
— Morris. 1843. Cat. Brit. Foss. p. 183. 
AcanrpEs Desnayesit. Sismonda. 1847. Method. Anim. invert. Pedemontii Foss. p. 57. 
— iG-zaG. Pictet. 1845. Traité élément. de Paléont. Vol. ii, p. 341. 
Naurrius (Ctymenta @) z1c-zac. Sow. 1849. Dixon’s Geol. Hist. &c. p. 109, pl. 8, fig. 19. 
Var. 3. Navrite pe Dax. De Monéf. 1802. Buffon de Sonnini Moll. vol. iv, pp. 240, 252, 
pl. 46, fig. 1. 
Navritus Pompiius. Lam. Ann. du Mus. vol. y, p. 181. 
— —_ — 1822. An. sans Vert. vol. xvi, p. 634. 
— DesnAyesit. Defr. 1825. Dict. de Hist. Nat. vol. xxxiv, p. 200. 
— Aturt. Bast. 1825. Desc. des Coq. foss. des Env. de Bordeaux, p. 17. 
Orputites z1c-zac. De Blainv. 1825. Man. de Malae. p. 387. 
Navritus (AcaNntDes) Aturt. D’Orb. 1825. Tab. method. de la Classe des Céph. p. 71. 
— Syrno. Buckl. 1836. Bridgw. Treat. vol. i, p. 357, pl. 46, figs. 1-4. 
— — Grateloup. 1838. Cat. des An. vert. et invert foss. du Basin de la 
Gironde, p. 28. 
Acanipes Arurt. Pictet. 1845. Traité element. de Paléont. Vol. ii, p. 341. ~ 
A, Testd ventricosd, levigatd ; umbilicis clausis ;  septis concavis ; lobis lateralibus 
angustis, acutis ; dorsalibus valde recurvis ; siphone magno, continuo, buccineforme. 
Var. B. Zestd compressa, sub-discoided ; septis profundé concavis, lobis dorsalibus 
angustioribus. 
Shell ventricose, smooth ; umbilicus closed; septa concave; lateral lobes narrow, 
pointed ; dorsal lobes much curved ; siphuncle large, continuous, trumpet-shaped. 
There are scarcely any tertiary remains which have excited so much attention as 
the present; not merely because the species is widely diffused, but because it presents 
an intermediate form between the Nautili and the Ammonites ; and few fossils have 
been referred to more genera, or have been distinguished by a greater number of 
specific names. 
The Aturia zic-zac was first described by Mr. Sowerby, sen., as Nautilus zic-zac, 
from a specimen which was found on forming the tunnel of the Highgate Archway. 
Several years afterwards M. Defrance described a specimen from the Paris basin, and 
pointed out the differences which, in his opinion, rendered it difficult to refer the 
species to the genus WVawtilus. M. Defrance considered the fossil described by him as 
distinct from the /V. 2¢c-zac, and gave to it the specific name Deshayesit. Subsequently 
Basterot described the well-known Dax fossil, which he named Naut. Atur’, and with 
which he considered the Nawt. zic-zac to be identical. M. d’Orbigny and Sig. 
Sismonda, not regarding the dorsal position of the siphuncle, but relying on the 
angular lobes which characterise the septa, have referred the shell in question to 
De Montfort’s Ayanides, a genus which, as has been before stated, was founded on a 
Goniatite from the mountain limestone. Michellotti, on the other hand, has considered 
