226 
NATJTILOIDEA. 
produced beyond the shell border, gives a beak-like termiuation to 
this part of the aperture, a feature which was noticed by Sowerby. 
The septa are direct and but slightly concave, they are distant from 
each other from ^ to i the long diameter of the shell. The siphuncle 
is close to the ventral border and its elements are nummuloidal. 
The shell ornaments are described by Blake from the type specimen 
as consisting of “ rough risings of growth which are easily lost, 
are not very regular, but which curve back very much towards tlie 
convex side, cutting the septa at an angle of GU°. On the base of 
the body-chamber in all specimens seen is a crenulatcd band, which 
is more or less feebly continued upon the lower part of the body- 
chamber. As a rule, I am not inclined to consider these marks as 
a specific character, for they may be absent or present ; but in this 
species their presence seems always accompanied by the other 
distinctive characters.” .... The type of this species is 
missing. 
Blake regards the species as represented in the Bohemian rocks 
by 6r. [Fhra^m.] comes, Barr., in which, however, the shell is more 
inflated, and shows no crenulations at the base of the body-chamber. 
Prom Gompli. \_PhrapnJ] imhricatum, G. arcuatum differs in the 
character of its ornamentation, but it resembles that species in 
other respects, as, for example, in the beak-like projection of the 
lesser orifice and in the general form of the shell. 
Horizon. Wenlock ; Lower Ludlow. 
Localities. Dudley ?, Worcestershire ; Leintwardine, Hereford- 
shire. 
Represented by two imperfect examples. 
Gomphoceras ventricosum, Sowerby, sp. 
1839. Phragmoceras ventricosum^ Sowerby, in Murchison’s Sil. Svst. 
p. 621, pi. X. ff. 4, 5, 6. 
1852. Phragmoceras ventricosum^ M^Coy, British Pal. Foss. fasc. ii. 
p. 322. 
1854. Phragmoceras ventricostcm, Morris, Cat. British Foss. 2nd ed. 
p. 312. 
1882. Phragmoceras ventricosum, Blake, British Foss. Ceph. pt. i. 
p. 200, pi. xxiv. ft‘. 1,1 a, 2, 2 a, 3. 
Sp. Char. Shell curved, but not sufficiently so to form a complete 
whorl ; the apical portion unknown. Section elliptical, the ratio of 
the two diameters, in an uncompressed example, being about as 
20 ; 27. The septa form a very open sigmoid curve in passing across 
the shell ; they are rather widely separated, being about the dia- 
meter distant from each other, as measured in the middle of the side 
