284 
NAUTILOIDEA. 
of the shell. The rate of increase is in the ratio of 1 to 3 in a 
length of 40 millim., measured in the septate part of the shell. 
The body-chamber occupies about ^ of the total length of the shell ; 
the aperture is a little oblique to the plane of the last septum. 
The distance between the septa equals about of the corre- 
sponding diameter of the shell. The siphuncle is situated close to 
the convex border of the shell, at a little distance from the test ; its 
elements are elongated and cylindrical. The surface of the test is 
ornamented with transverse, imbricating striae, covered with ex- 
tremely fine lines running in the same direction ; in some specimens 
the latter are obsolete. 
Eemarhs. M. decijpiens, Barr. (pi. cliv.), is very closely allied to 
M. velooc, but it has a more rapid rate of increase and is much less 
curved. 
Horizon. Etage E, bande el {= Salopian). 
Locality. Butowitz, Bohemia. 
Eepresented in the Collection by a single example. 
Beevicones. 
Cyrtoceras (Meloceras) acutiim, Barrande, sp. 
1848. Cyrtoceras acutum, Barrande, Haidinger, Berichte fiber die 
Mittheil. von Freund, d. Naturwiss. in Wien, Band iv. p. 209. 
1852. Cyrtoceras acutum, Giebel, Fauna der Vorwelt, Band iii. Abth. i. 
p. 209. 
1867. Cyrtoceras acutum, Barrande, Syst. Sil, de la Boheme, vol. ii. 
pt. i. p. 539, pi. cli. ff. 1-10. 
Char. Curvature very slight ; upon a chord of 30 millim., sub- 
tending the concave side, the highest perpendicular is only 2 millim. 
The transverse section is circular. The rate of increase in the septate 
part of the shell is about 2 in 3. Body-chamber greatly developed, 
its length being equal to nearly | the diameter of the aperture, or 
half that of the entire shell. The aperture has neither sinus nor 
constriction. The septa are distant from each other about i the 
diameter of the shell. The siphuncle is cylindrical, and is situated 
close to the external border of the shell. The test is ornamented 
with fine transverse, somewhat regular raised lines, while a series 
of very faint longitudinal lines may be seen, under a low magnifying- 
power, crossing them. 
RemarJcs. The species that has the nearest resemblance to this 
one is M. sequacc, Barr. (pi. clii.), but it is distinguished by its 
larger siphuncle and by the character of its ornaments. 
Horizon. Etage E ( = Salopian). 
