238 
NATJTILOIDEA. 
Sp. Char, Shell curved on the dorsal, but nearly straight on the 
ventral border. Transverse section oval, the ratio of the ventro- 
dorsal to the transverse diameter being as 6:5. The rate of 
increase is very rapid, being 1 in 2 in the septate part of the shell. 
The body-chamber occupies about ^ of the total length of the shell, 
while in bulk it nearly equals that of the septate part. The 
general surface of the aperture is a little oblique to the plane of the 
last septum. The larger orifice is situated at the most elevated 
part of the aperture ; the two pairs of lobes into which it is divided 
being distinctly separated from each other, with a broad and shallow 
median saddle. The longer pair of lobes are inclined towards the 
dorsal border of the shell, the shorter towards the ventral border. 
A long channel leads to the smaller orifice, which projects consider- 
ably beyond the ventral border in a beak-like fashion. The septa 
are moderately distant from each other, being on an average 
about yL of the shell- diameter apart ; they arch strongly upwards 
on the dorsal side. The siphuncle is situated midway between the 
centre and the ventral border, though in the young shell it is closer 
to the margin ; its elements are nummuloidal and slightly flattened, 
the breadth being to the height in the ratio of 8 to 5. The test 
is ornamented with subregular striae of growth, which tend to form 
more or less prominent thread-like lines. In the vicinity of the 
aperture these lines naturally conform to the outline of the orifices. 
The cast of the body-chamber exhibits a series of irregular longi- 
tudinal impressions very slightly raised above the surface ; these 
have apparently some connection with the crenulations observed at 
the base of the body-chamber in certain specimens. 
Remarhs. This species comes very near to Tetrameroceras^Phragni.) 
Loveni, Earr., in its general shape, and in the characters of the 
aperture, but it has a slower rate of tapering and is not so decidedly 
curved as that species. 
Horizon. Etage E (Salopian). 
Locality. Lochkow, Bohemia. 
Represented in the Collection by a single example. 
Tetrameroceras Loveni, Barrande, sp. 
1854. Phragmoceras Loveni^ Barrande, Leonhard and Bronn’s Nenes 
Jahrb. Heft i. p. 11. 
1867. Phragmoceras Loveni, Barrande, Syst. Sil. de la Boheme, vol. ii. 
pt. i. p. 227, pi. xlviii. ff. 8-11, pi. xlix. if. 16-19, pi. xcix. ff. 8-11 
(young). 
Sp. Char. Shell strongly convex on the dorsal side and but 
slightly concave on the ventral. Transverse section oval, the two 
