CEPHALOPODA. 53 



NAUTILUS zic-zac. Nyst. 18-13. Pull. Soc. Cool, dc France, vol. xiv, p. 452. 



— — — 184.3. Desc. des Coq. foss. &c. des Terr. tcrt. delaBclgique, 



p. fill, pi. 46, fig. 4. 



— — Morris. 1843. Cat. Brit. Foss. p. 183. 



Aganides Desiiayesii. Sismonda. 184". Method. Aniin. invert. Pedcmontii Foss. p. 57. 



— zig-zag. Pictet. 1845. TraitS element, de Paleont. Vol. ii, p. 341. 

 Nautilus (Clymenia?) zic-zac. Sow. 1849. Dixon's Geol. Hist. &c. p. 109, pi. 8, fig. 19. 

 Var. ft. Nautile de Dax. Be Mont/. 1802. Button dc Sonnini Moll. vol. iv, pp. 240, 252, 



pi. 46, fig. 1. 

 Nautilus Pompilius. Lam. Ann. du Mus. vol. v, p. 181. 



— — — 1822. An. sans Vert. vol. xvi, p. 634. 



— Desiiayesii. Befr. 1825. Diet, de l'Hist. Nat. vol. xxxiv, p. 200. 



— Aturi. Bast. 1825. Desc. des Coq. foss. des Env. de Bordeaux, p. 17. 

 Ohbulites zic-zac. Be Blainv. 1825. Man. dc Malac. p. 387. 



Nautilus (Aganides) Aturi. B'Orb. 1825. Tab. method. delaClasse des C6ph. p. 71. 



— Sypiio. Buckl. 1836. Bridgw. Treat, vol. i, p. 357, pi. 46, figs. 1-4. 



— — Grateloup. 1838. Cat. des An. vert, et invert foss. du Basin de la 



Gironde, p. 28. 

 Aganides Atuki. Pictet. 1845. Traite element, de Paleont. Vol. ii, p. 341. 



A. Testa ventricosd, laevigata ; umbilicis clan sis ; septis concavis ; lobis lateralibus 

 angustis, acutis ; dorsalibus valde recurvis ; siphone mag/io, continuo, buccinaformi. 



Var. /3. Testa compressd, sub-discoided ; septis prof wide 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 Nautilus. M. Defrance considered the fossil described by him as 

 distinct from the N. zic-zac, and gave to it the specific name Deshagesii. Subsequently 

 Basterot described the well-known Dax fossil, which he named Naut. Aturi, and with 

 which he considered the Naut. 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 Aganides, a genus which, as has been before stated, was founded on a 

 Goniatite from the mountain limestone. Michellotti, on the other hand, has considered 



