324 
XAUTILOTDEA. 
importance of that which distinguishes X. Parl'uisoyii. The dorsal 
lobes are much recurved and obliquely truncated ; the siphuncle is 
moderately large, placed very near to the dorsal margin, and con- 
tinuous. The striae of growth towards the middle are suddenly 
bent backwards in deep undulations.” {EJ wards.) 
Eemarks. This species is distinguished by the extreme narrow- 
ness of the periphery, which causes the umbilical region to appear 
very prominent, and gives a distinctly lenticular form to the shell. It 
is said by Edwards to have been common in the Isle of 8heppey and 
at Bognor. 
The largest specimen in the Collection (Xo. 16157) measures 10 
inches in its greatest diameter. The specimen (Xo. 32726) figured 
by Dixon is nearly as large. Unfortunately neither of these 
specimens is localized. 
Horizon. London Clay (Lower Eocene). 
Localities. Holloway, Potter’s Bar, Whetstone, Finchley ; Middle- 
sex : Isle of Sheppey. 
Well represented in the Collection, which includes the specimen 
(No. 32726) part of which was figured by Dixon in the ‘ Geology 
of Sussex,’ pi. xiv. f. 15. No. 16157 was presented by E. H. 
Handley, Esq. 
Sijyecies of Doubtful Validity. 
The following species, viz. Xautilus ellijiticus, Schafhautl, and 
X. macrocephalus, Schafh., from the Eocene formation of Kressen- 
berg \ Bavaria, are casts in a coarsely granular matrix upon which 
not an atom of the test is preserved, though the sutures of the 
septa are traceable, more or less imperfectly, in all the specimens. 
Under these circumstances one is very much inclined to doubt the 
validity of such species, in which, owing to the coarseness of the 
matrix, so many characters, required to found species upon, are 
wanting. 
Nautilus ellipticus, Schafhautl. 
1852. Nautilus ellipticus, Schafhautl, Der Teisenberg oder Kressenberg 
in Bayern, in Leonhard and Bronn’s Neues Jahrbuch fiir Min. 
&c. p. 165. 
^ A mountain in the district of Traunstein, Upper Bavaria. A full descrip- 
tion of the Kressenberg Beds may be seen in Giimbel’s “ Geogn. Beschreibung 
des bayerischen Alpengebirges und seines Yorlandes,” Geogn. Karte des 
Kbnigreiches Bayern, 1861, pp. 586-602. 
