274 Messrs. Foord and Crick on new and 



Sp. char. Shell inflated, rapidly enlarging; sides com- 

 pressed, but somewhat inflated in the middle ; periphery 

 broad, flattened. Umbilicus of moderate size and exposing 

 a portion of the inner whorls ; sides steep, margin rounded. 

 Septa rather distant, being 2^ inches apart where the whorl 

 has a height of about 6 inches. Siphuncle rather large, 

 situated above the centre. The lest is ornamented in the 

 adult shell with a series of longitudinal flattened bands sepa- 

 rated by incised lines ; these bands are almost entirely con- 

 fined to the periphery, very few of them extending to the sides 

 of the shell ; they number about thirteen to an inch. The 

 whole of the test is covered with fine subregular lines of 

 growth, which curve backwards on approaching the periphery, 

 where they form a shallow sinus. In a young shell (4£ 

 inches in diameter, see fig. 7) the longitudinal ornaments 

 cover the whole surface of the test, and they are in the form 

 of delicate irregularly-spaced ridges, with very fine lines 

 occupying the interspaces. The ridges are more numerous 

 on the periphery than on the sides of the shell. 



Remarks. The adult characters of the ornamentation of 

 this species have been drawn up from a gigantic specimen, 2 

 feet in diameter, which was found at Sherborne, Dorsetshire. 

 This is probably one of the largest examples of Nautilus 

 known ; at least the writers have never seen any account of 

 a specimen approaching it in size. A smaller one from the 

 same locality (Sherborne) measures 11 inches in its greatest 

 diameter ; it is a cast of the septate part of the shell, together 

 with a portion of the body-chamber. Fragments of the test 

 with its characteristic ornaments adhere to the cast in one or 

 two places. 



This species, in respect to its ornamentation, bears some 

 resemblance to N. Jourdani of the Upper Lias, but can be at 

 once distinguished by its less angular whorls and the rounded 

 margin of the umbilicus. The latter character also distin- 

 guishes it from N. tertbratus from the same beds, whose orna- 

 ments, like those of the adult shell of N. ornatus, are almost 

 entirely confined to the peripheral area. There are no other 

 species known to us from the Inferior Oolite with which this 

 form can be confounded. 



Horizon. Inferior Oolite. 



Locality. Near Sherborne, Dorsetshire. 



7. Nautilus lijieatus, J. Sowerby. 



1813. Nautilus lineatus, J. Sowerby, Min. Conch, vol. i. p. 89, pi. xH. 

 ? 1 820. Natdtiite s aperturatus, Scnlotheim, Die Petrefactenkunde, 



p. 8-3. 



