180 
NAUTIIOIDEA. 
Actinoceras lamellatam, Angelin, sp. 
1880. Ortlioceras la^nellatum, Angelin and Lindstrom, Fragmenta Silu- 
rica, p. 6, tab. vii. ff. 24-26. 
1885. Orthoceras lamellatum, Lindstrom, List of the Fossils of the 
Upper Silurian Formation of Gotland, p. 6. 
Sp. Char. Shell straight. Section slightly elliptical, the ratio of 
the two diameters being as 32 : 35. Septa numerous, distant 2^ 
lines, where the diameter of the shell is 2L inches, and maintaining 
about the same distance in a specimen measuring 5 inches in length ; 
forming a broad, shallow sinus in the region of the siphuncle, and 
arching upwards laterally. Diameter of the siphuncle measuring 
|- that of the shell. Test smooth, according to Angelin, but with 
faint longitudinal lines upon the cast of the chambers. 
Horizon. Upper Ludlow. 
Locality. Island of Gothland, Sweden. 
The Collection contains two specimens presented by A. H. Foord. 
Actinoceras imbricatum, Hisinger, sp. 
Fig. 24. 
Actinoceras imhricatum. — a, fragment of a cast, showing the disposition of the 
septa on the siphnncular aspect ; b, section of a smaller individual, show- 
ing the large nummuloid siphuncle sc, and the septa, s ; c, transverse sec- 
tion, showing the position of the siphuncle {si) and its diameter between the 
necks of the septa, a and b of the natural size ; c, reduced 4- 
