GOMPHOCERITID^. 
227 
of the shell. “ The siphuncle is seen in several to be internal ; it 
is elliptic in section, the long diameter in the plane of curvature 
reaching J- that of the septum ’’ (BlaJce). The ornamentation, which 
is a very marked feature in the species, consists of upwardly imbri- 
cating striae, which make a bold curve on the sides of the shell, 
forming on the convex (dorsal) margin a broad sinus, and upon the 
concave (ventral) margin a tongue-like lobe, pointing away from 
the aperture. The larger apertural orifice forms a broad transverse 
opening, raised above the general level, the channel uniting it with 
the smaller orifice being partJy closed. 
Remarks. The species most closely allied to the present one is G. 
[PArar/m.] imhricatum, liarrande, sp., but this has a stronger curva- 
ture, and the striae upon the surface of the test are more irregular 
than they are in the present species. Added to this, P. imlricatum 
increases more rapidly in diameter than does G. ventricosum. The 
latter has undoubted affinities also with G. [Phrafjm.'j Brocleripi, 
Barr., as Blake has pointed out {Joe. cit. p. 201) ; but from a com- 
parison of the British and Bohemian species, I find that the orna- 
mentation in Brocleripi is of a much coarser character than that of 
ventricosum, and this alone would be quite sufficient to distinguish 
these two species. 
Horizon. Wenlock ; Lower Ludlow. 
Localities. Dudley, Worcestershire ; near Ludlow, Shropshire ; 
(xarcoed, near Usk, Monmouthshire. 
Bepresented in the Collection by several remarkably fine spe- 
cimens ; those from Garcoed and Ludlow presented by J. E. Lee, 
Esq., F.S.A. 
Gomphoceras Broderipi, Barrande, sp. 
1847. Phrac/moceras Broderipi, Barrande, Haidinger, Berichte fiber die 
Mittheil. von Freund, d. Naturwiss. in Wien, Band iii, p. 269. 
1867. Phragmoceras Broderipi, Barrande, Syst. Sil. de la Boheme, 
vol. ii. pt. i. p. 207, pi. Ivi., pi. Ivii., pi. Iviii., pi, Ixv. f. 3, pi. xcviii. 
ff. 1-4, pi. xeix. ff‘. 1-7. 
Bp. Char. Shell strongly curved, so as to form a complete whorl. 
The apical extremity of the shell is blunt, and terminates in a 
spherical cap {calotte)^. The transverse section is of an oval form, 
of which the narrowest end corresponds with the concave or ventral 
side of the shell. The ventro-dorsal axis is to the transverse as 
5 : 4. The increase in diameter is very rapid, being in the ratio 
of 1 : 10. The body-chamber occupies about half the length 
‘ Figured by Barrande tjoc. cit.) in plates Ivi., Ivii., Iviii., xeix- 
q2 
