272 
NAUTILOIDEA. 
large. The septa are not oblique, rather close, concave, considerably 
arched backwards on the sides, and therefore projecting forwards on 
the ventral and dorsal aspects. They are crowded on the inner side 
of the curve, and of course wider apart on the outer margin. 
“ The whole fragment is two inches long ; the last chamber is not 
preserved in our single specimen, nor have we the pointed apex, 
which was probably more curved than the older part of the shell.” 
Bemarhs. The specimen is very imperfect ; the most remarkable 
feature about it is the great proportionate distance of the septa from 
each other ; I can find no species of the size of the present one in 
which the septa are so wide apart. 
Horizon. Lower Silurian (Ordovician ?). 
Locality. Rimkin, Himalaya Mountains. 
Represented in the Collection by the specimen figured and 
described by Salter, which was transferred from the Museum of 
Practical Geology. 
SILURIAN SPECIES, 
a. Exogastric. 
Cyrtoceras (Meloceras) compressum ?, J. de C. Sowerby, sp. 
1839. Thragmoceras compressum, J. de C. Sowerby, in Miu’chison’s 
^ Silmian System,’ pt. ii. p. 621, pi. xi. f. 2. 
1854. Bhragmoceras compressum, Salter, in Murchison’s Siluria, pi. xxxi. 
f. 4. 
1873. Cyrtoceras ? compressum, Salter, Cat. Cambr. and Silur. Foss. 
p. 160. 
1876. Phragmoceras compressum, Armstrong, Young, and Robertson, 
Cat. of Western Scottish Fossils, p. 21, 
1882. Cyrtoceras compressum, Blake, British Foss. Ceph. pt. i. p. 177, 
pi. xviii. fi. 1, 2. 
Sp. Char. “ The section was probably elliptic, but in none is it 
perfectly preserved. The rate of increase is about 1 in 5 in the 
earlier portions, or even greater from contortion, but reduces to 
almost zero at last. The mean curvature is considerable, having a 
radius of 1 J inches when the mean diameter of the shell is more than 
1 inch. The body-chamber is as long as its basal diameter, and 
shows no change at the aperture. The ornaments, when preserved, 
are transverse sharp lines of growth, rather sigmoid in outline, and 
cutting the sutures towards the outside. The septa are approximate, 
concave on the side, but really sigmoid ; they are very close, occa- 
sionally extremely so. The siphuncle is external and bulbous.” 
(BlaJce.) 
Bemarhs. The specimens 1 have referred to this species are very 
