LITTJITID^. 
11 
Localities. Dudley, Worcestershire; Denbighshire 
(W. S.) ; Ludlow, Shropshire (L. L.). 
Eep resented in the Collection by three examples, one of which 
(Xo. 37899) is figured by Blake (loc. cit. pi. viii. fig. 15). 
Ophidioceras geometricum, Blake. 
1882. Ophidioceras c/eometricum, Blake, British Foss. Ceph. pt. i. p. 231, 
pi. xviii. fF. 16, 16 a. 
Sp. Char. “ The rate of increase is I’o and the last whorl -31 of 
the whole, the whorls being just in contact. The last chamber leaves 
the earlier whorls for some space. The character of the section is 
not seen. The aperture is bounded by sigmoid lines, and has an 
inflation on the inner side, giving it a proboscis-like form. The 
ornaments are subacute, separate ribs, which run radially, and 
appear to be lost on the front, which has the same appearance of a 
keel as in Oph. articulatiim. There are 32 per whorl, but they die 
away on the straight portion, which has only lines of growth. The 
whorl is crossed by a number of sharp spider-lines, which pass across 
the ribs so as to transgress nearly a rib-interval in their passage 
outwards ; these are eight per space. Diameter 1 inch Two 
other specimens from different localities show the peculiarities of 
this form ; the rate of increase being 1'53, and the last whorl *33 of 
the diameter. The aperture is seen only in the type. The ribs may 
be as few as 27 per whorl, and bent back towards the outside, but 
there is the same appearance of a keel, probably due to a flat band, 
in all, and the remarkable thread-like lines transgressing the ribs, 7 
per space. Xo septal characters are anywhere seen The pre- 
sent species has a broader last whorl and greater rate of increase 
than any of those referred to Oph. articulatum. The ribs are perhaps 
not quite so straight ; and, above all, though specimens of the last 
named, with ornaments perfectly preserved, have been seen, they do 
not show the remarkable transgressive threads of the present 
[species].” (BlaJee.) 
liemarlcs. A specimen from Xantglyn, much crushed and distorted, 
is referred very doubtfully to this species. The ribbing, however, 
can be seen, and the shell appears to taper more rapidly than that 
of Oph. articulatum. It is also a larger shell than the latter. 
Horizon. Wenlock Shales. 
Localities. Dudley, Worcestershire ; Xantglyn, Denbighshire. 
Represented in the Collection by four specimens, one of which 
(No. 73896) is figured by Blake {loc. cit. pi. xviii. fig. 16). 
