XAUTILID^. 
309 
Nautilus d’Orbignyanus, Eorbes. 
1846. Nautilus d' Orbignyanus, Forbes, Descriptions of Secondary Fossil 
Shells from South America, in Darwin’s ‘‘ Geological Observations 
on Coral Reefs, Volcanic Islands, and on South iimerica (Voyage 
of the ‘ Beagle ’),” Appendix, p. 265, pi. v. ff. 1 «, 1 b. 
1850. Nautilus Dekayi, d’Orbigny (pars, non Morton), Prodr. de 
Paleont. Stratigr. vol. ii. p. 211. 
Bp. Char. “ Shell ventricose (probably smooth and slightly um- 
bilicated ?). Mouth very broad, reniform. Back rounded. Sutures 
bend suddenly towards, and nearer to, the umbilicus ; on the back 
they are very slightly sinuated.” {Forbes.) 
Remarlcs. Forbes further observes that “the form of the chambers 
resembles that seen in Nautilus Bowe7'byanus ; ” but he adds, “ the 
general form more nearly resembles Nautilus Icevigatus [now called 
sublcevigatus~\ of the same author.” 
Horizon. Cretaceous. 
Locality. Concepcion, Chile. 
Represented in the Collection by the specimen figured in Darwin's 
“ Geological (3bservations ” {loc. at.). 
Nautilus, sp. 
Some specimens collected in “ Southern Peru, near the borders of 
Bolivia, from high mountain-ranges,” are in such a weathered and 
imperfect condition as to render it impossible to identify them speci- 
fically. One of them (No. 74108 {a)) resembles in many respects 
a specimen figured by MM. Bayle and Coqiiand ^ under the name of 
Nautilus striatiis, J. Sow. They thus describe their fossil : — 
“ Coquille largement ombiliquee, a dos large ; cloisons assez rap- 
prochees, legerement flexueuses, conservant pres de Pombilic, qui 
est large, des stries fines et tres rapprochees, dirigees suivant I’en- 
rouleinent en spirales de la coquille.” 
This description agrees fairly well with the British Museum fossil 
(No. 74108 (a)), though the septa in the latter are more numerous 
than they are represented to be in Bayle and Coquand’s figure. No 
trace of the test remains in the British-Museum specimen, which, in 
common with the other Peruvian examples, is silicified, causing the 
jagged edges of the septa to project a little from the matrix, which 
is composed of a softer material. The siphuncle is not seen. 
^ Mem. Soc. Geol. de France, 1851, ser. ii. vol. iv. pt. i , “ Mem. sur les Fos- 
siles recueillis dans le Chili, par M. Tgnace Domeyko,” p. 8, pi. ii. f. 6. 
