imperfectly -defined Species of Jurassic &c. Nautili. 393 



neighbourhood being of Carboniferous age. It is true that the 

 siphuncle is represented in Sonnini's figure as nearly central 

 but this might have been a mistake on "the part of the artist. 

 ft would at any rate be impossible to settle this question 

 without a reference to the original specimen, and in the mean- 

 while it would not be advisable to adopt Montfort's name 

 Aganides so long as there is any uncertainty about the type 

 specimen *". 



Jurassic. 

 1. Nautilus lineolatus, sp. nov. 



Sp. char. Shell thick, somewhat inflated on the sides, with 

 a broad and flattened periphery ; greatest breadth of the whorls 

 at about the middle of the sides ; aperture wider than high, 

 presenting a distinctly subquadrate section. Umbilicus very 

 small and deep, with rounded border. Septa moderately 

 distant ; sutures rather concave on the sides of the shell and 

 forming a very slight sinus on the periphery. Siphuncle not 

 seen. Test thick, ornamented with subregular lines of growth. 



A large example from Vetney Cross, Dorsetshire, measures 

 6 inches in diameter and 4 inches in its greatest breadth. 



Remarks. This species is closely allied to Nautilus clausus, 

 d'Orbigny, but it is distinguished by its less rapid rate ol 

 increase, by its open umbilicus, and on the whole by its more 

 compressed form. The body-chamber of a young example 

 (no. 36952) exhibits traces of the anterior border of the im- 

 pression of the shell-muscle. 



We have not thought it necessary to figure this species, on 

 account of its great similarity to N. clausus. 



A small specimen from the Upper Lias of Fontaine-Etoupe- 

 Four probably belongs to this species. 



Horizon. Inferior Oolite (England) ; Upper Lias (France). 



Locality. Yeovil, Somersetshire (no. 36952) ; Vetney Cross, 

 Dorsetshire; Fontaine-Etoupe-Four (Calvados), France. 



2. Nautilus (Hercoglossa) aganiticus, Schlotheim. 



1820. Nautilites aganiticus, Schlotheim, Die Petrefaetenknnde, p. 83. 

 1858. Nautilus aganiticus, Oppel, Die Juraformation Englands, Frank- 



reichs und des siidwestl. Deutscblands, p. 686. 

 1868. Nautilus aganiticus, Zittel, " Die Cephalopodeu der Stramberger 



Schichten," in Oppel and Zittel's ' Palseontologische Mittheilungen,' 



Band i. Abth. ii. p. 43. 



Sp. char. Shell somewhat inflated, slightly compressed on 

 the sides, rather narrowly rounded on the periphery. Unibili- 



* See remarks on the name Aganides by Meek (too long for insertion 

 here), United States Geol. Surv. Terr. vol. ix. 1876, p. 494. 



Ann. & Mag. N. Hist. Ser. 6. Vol. v. 28 



