222 
NATJTILOrDEA. 
and the smaller orifice, together with the channel connecting them, 
are greatly contracted. The larger orifice is slightly arcuate, and 
the lobes at either extremity of it are but very little expanded. The 
distance between the septa does not exceed i of the diameter of the 
shell ; they are, however, very strongly convex, particularly in spe- 
cimens which have not attained adult age ; the convexity equals 
sometimes the diameter of the shell. The siphuncle is situated 
in the median line between the ventral margin and the centre, a 
little nearer to the former than to the latter. It is for the most 
part cylindrical, but tends to become inflated in the vicinity of the 
body-chamber. The test has no other ornamentation than lines of 
growth, more or less distinct, but somewhat irregularly spaced. 
Horizon. Etage E (= Salopian). 
Localities. Kosofz, Lochkow, Bohemia. 
Fairly well represented in the Collection. 
Gomphoceras perversum, Barrande, sp. 
1854. Phraqmoceras perversum, Barrande, Leonhard and Broun’s Jahrb. 
Heft i. p. 10. 
1867. Phragmoceras perversum, Barrande, Syst. Sil. de la Boheme, 
vol. ii. pt. i. p. 241, pi. liii. ff. 1-33 (pi. c., vars. suhrecta and fal- 
ciformis). 
Sp. Char. This small species varies much in the degree of its 
curvature, some examples being very strongly curved, whilst others 
are scarcely bent at all. Barrande has separated two varieties 
from the species, under the names of 
Yar. subrecta slightly curved. 
Yslt. falciformis much curved. 
The transverse section is oval or suboval, the ratio of the two dia- 
meters being as 7:6. The rate of increase, computed from one of 
the straighter examples, is 1 in 4|. The body-chamber varies very 
much in its relative size, being sometimes |-, sometimes only of the 
total length of the shell. The aperture presents a great diversity 
of form, the larger orifice ^sometimes projecting to such an extent 
as to overhang considerably the shell-border, or it may scarcely pro- 
ject at all. The whole of the aperture, including the two orifices 
with the channel connecting them, is raised considerably above the 
surface of the shell. The larger orifice is semicircular, and con- 
nected by a narrow channel with the smaller one, which is formed 
by a very slight expansion of the channel. The septa are very close 
together, their mean distance amounting to about J the ventro- 
dorsal diameter. The siphuncle is situated very near to the ventral 
