216 
NATJTILOIDEA. 
SILUEIAN SPECIES, 
a. Exogastric. 
Gomphoceras cinctum, Blake. 
1882. Gomphoceras cinctum, Blake, Britisk Foss. Cepb. pt. i. p. 197, 
pi. xxiii. ff. 5, 5 a. 
Sjo. Char. “Section elliptic; diameters in the ratio of 16 to 13. 
General outline straight with little convexity, like two cones with 
their bases opposed. The septate portion increases in its long 
diameter at the rate of 1 in 2. The greatest thickness is at the 
last septum, from which the body-chamber contracts again at the 
rate of 2 in 3. There is a constriction at the base of the body- 
chamber and another round the aperture, which is not weU shown, 
but the dorsal opening of which appears to have a simple elliptic 
outline. Septal characters not seen.” (BlaJee.) 
RemarTcs. The above description is that of the type specimen, 
which, as may be seen, is in a very imperfect condition. Other 
specimens show that the septa are but slightly convex and are 
distant from each other -1 the greatest diameter of the shell. The 
siphuncle is not more than ^ the diameter from the ventral side. 
Prof. Blake considers that this species “ approaches G. microstoma, 
Barrande, but there is no reason to believe that the ellipticity of our 
species is due to compression, as they are found with the same cha- 
racters in different localities.” 
Horizon. Lower Ludlow. 
Locality. Ludlow, Shropshire. 
Represented by the type specimen, figured by Blake. 
Gomphoceras crater, Blake. 
1882. Gomphoceras crater, Blake, British Foss. Ceph. pt. i. p. 189, 
pi. xxiii. ff. 4, 4 a, 4 6, 8, 8 a. 
/Sp. Char. “ Section circular ; the general direction of the shell 
straight. The body-chamber, which alone is preserved, has straight 
sides, so that it forms a cone. Its length is | the basal diameter. 
The aperture has the dorsal opening on the apex, which is trans- 
versely elliptic, with axes in the ratio of 3 to 2. The passage and 
ventral opening are not distinct, but form, as it were, a long lobe, 
which slopes down the ventral side. The whole is separated from 
