CTKTOCEEATID-®. 
279 
spends with the convex border of the shell. It should be observed 
that this border narrows very considerably, so that it forms in some 
specimens an obtuse keel along the median line. The dorso-ventral 
axis of the shell is to the transverse as 17 : 14. The rate of increase 
is in the ratio of 4 to 7, in a length of 40 millim. measured in the 
septate part of the shell ; it is less above. The body-chamber occu- 
pies nearly ^ of the total leugth of the shell ; it is a little constricted 
near the aperture ; there are crenulations at the base in some speci- 
mens h The aperture is nearly parallel to the plane of the last 
septum. The septa are distant from each other about of the 
diameter of the shell ; the sutures have a slightly sinuous outline 
and point forward along the median line of the convex side of the 
shell. The siphuncle is situated close to the peripheral margin of 
the shell ; its elements are cylindrical. The surface of the tost is 
marked with irregular lines of growth, which form a very distinct 
sinus upon the convex side of the shell. A series of faint longitu- 
dinal and transverse lines are seen upon the cast. 
Remarlcs. The species having the closest resemblance to this one 
is M. Geinitzi^ Barr. (pi. exxii.) ; but the latter has a much more 
flattened transverse section, its body-chamber is shorter, and its 
siphuncle nearer to the margin. 
Horizon. Etage E (= Salopian). 
Locality. Lochkow, Bohemia. 
\Yell represented in the Collection. 
Cyrtoceras (Meloceras) imperiale, Barrande, sp. 
1848. Cyrtoceras wiperude, Barrande, Haidinger, Berichte iiber die 
Mittheil. von Freund, der Naturwiss. in Wien, Band iv. p. 209. 
1852. Cyrtoceras imperiale, Giebel, Fauna der Vorwelt, Band hi. Abth. 
i. p. 209. 
1867. Cyrtoceras imperiale, Barrande, Syst. Sil. de la Boheme, vol. ii, 
pt. i. p. 510, pi, cxi,, pi. ccviii. ff . 17-20. 
8p. Char. The shell has a considerable curvature, especially in 
the apical portion. Upon a chord of 100 millim. subtending the 
concave side, the highest perpendicular is 20 millim. The transverse 
section is elliptical, of which the ventro-dorsal is to the transverse 
axis as 22 : 19. The increase in the lower half of the shell is in the 
ratio of 1 to 3, in a length of 60 millim. The body-chamber is not 
well developed ; its length is about | that of the entire shell. The 
aperture is parallel to the plane of the last septum. The distance 
of the septa from each other amounts to about the diameter of 
See one of the specimens registered No. 80332 in the Museum Collection. 
