142 
ance. The whirls are narrow, but deep, and marked with frequent 
transverse ridges, which bifurcate at their origin : a deep rounded 
groove seeming to terminate the first whirl. A similar termination 
of the first whirl is observable in the fossil, Fig. 10, to which fossil it 
somewhat approximates. 
Different opinions have been entertained with respect to the ammo- 
nites assuming naturally an oval shape. Whilst this has been said to 
be the case by some, who have adduced specimens of this fossil in this 
form, in proof of their assertions, others have contended, that the oval 
figure has proceeded from compression. The only specimen in this 
form, which I for some time possessed, was entirely pyritous ; and by 
observing that a part of the specimen retained the appearance and 
proportions of a round specimen, I hesitated at admitting the proof of 
the fact, from that instance. Since then, I have seen oval specimens, 
indubitably possessing their original form, from Wiltshire ; and have 
lately obtained one myself from Steyning, which is represented Plate 
IX. Fig. 6, and proves, undoubtedly, that shells of this genus existed 
originally in this shape. 
LXXVIII. Baculites. A straight, cylindrical, or slightly conical 
shell, divided into chambers by transverse, sinuous, and imperforated 
septa ; the articulations, or sutures, being indented in the manner of 
the battlements of a tower. 
The fossil, the characteristics of which are here given, was found by 
Faujus St. Fond, among the fossils of St. Peter’s Mountain, and was by 
him considered as a straight Cornu ammonis. Histoire Naturelle de la 
Mont, de St. Pierre , p. 140. The propriety of forming with it a distinct 
genus, as Lamarck has done, is obvious ; since, on the same principle 
that St. Fond would name it Ammonites rectus , we ought to place the 
orthoceratites under the genus Nautilus, and name it Nautilus rectus, 
as has been done by Baron le Hupsch, who has given a figure of this 
fossil ( Baculites •) accompanied with observations on its structure, and 
on the relationship which it bears to the Cornu ammonis. Nouvelles 
