4 
NAUTILOIDEA. 
Remarks. The most characteristic feature in the present species 
is the sculpture of the test, which is beautifully preserved on most 
of the specimens that have come before me. The figure (1 h) will 
enable the reader to realize the sculpture of the shell much better 
than a verbal description can do. It is necessary, however, to 
state that the riblets vary in width, so that in some places nearly 
five of them are contained in the space of 1 line, while in others, 
especially at the larger extremity of the shell, only about are 
required to fill that space. Ordinarily about 4 to 4^ are contained 
in 1 line. These measurements include the interspaces. 
The dimensions of the largest specimen in the National Collection 
are as follows : — length 11 inches, greatest diameter 2 inches, least 
diameter 1 inch. Septa about J inch apart, hut becoming a little 
closer near the smaller extremity of the shell. 
The very characteristic ornamentation of this species separates it 
from all other Ordovician species known to me. 
Horizon. Or^Aoceras-Limestone ^ (=Arenig). 
Localities. Kinnekulle Hill (Westrogothia), and Oeland, Sweden. 
Eepresented by a few good specimens : No. C 1951 presented by 
J. E. Lee, Esq., "e.S.A., E.G.S. ; No. C2029 by A. H. Eoord, E.G.S. 
Orthoceras Revalense, Eoord. 
1887. Orthoceras Revalense, Eoord, Ann, & Mag. Nat. Hist, ser. 5, 
vol. XX. p. 402, f. 3. 
Sp. Char. Shell straight. Section elliptical, the ratio of the 
diameters being as 24 : 19. Yery uniformly tapering at the rate of 
1 in 6. Septa direct, undulating ; distant about -J- the diameter. 
Siphuncle eccentric, cylindrical, its diameter about J the longer 
diameter of the shell. Body-chamber and test unknown. 
BemarTcs. The distinguishing feature of this species is its rela- 
tively high rate of tapering. 
Horizon. Orthoceras-JAmestone (=Arenig-Llanvirn). 
Locality. Eeval (Esthonia), Eussia. 
One specimen, presented by E. Hubbard, Esq. 
’ See a valuable paper by Prof. F. Schmidt, of St. Petersburg, “ On the 
Silurian (and Cambrian) Strata of the Baltic Provinces of Eussia, as compared 
with those of Scandinavia and the British Isles,” in Quart. Journ. Geol. Soc. 
vol. xxxviii. p. 514 (1882). Also J. E. Marr, on the “ Classification of the Cam- 
brian and Silurian Eocks,” pp. 74 & 82 (1883). 
