80 
KAUTILOIDEA. 
following : — (1) Ban atidcoceras ^ttrnhergi (pi. xxxvi.), which has 
its volutions only just touching each other, and they are also 
thicker ; the septa also are much more distant. (2) B. Bacheri 
(pi. xxxix.) is relatively of much smaller size, and is ornamented 
with striae disposed in groups. (3) B. t)/rannus (pi. xxxviii.) en- 
larges much less rapidly ; its body-chamber is longer and its 
siphuncle narrower. There are two specimens in the Collectioi], 
from the British Wenlock beds, which belong undoubtedly to this 
species. They both show some of the septa, with their sigmoidal 
sutures, together with part of the body-chamber, aud in one of them 
the subcentral siphuncle is seen. 
Horizon. Etage E (=Salopian). 
Localities. British: England (precise locality unknown). Foreign: 
Karlstein, Bohemia. 
Well represented in the Collection, which contains specimens in 
different stages of growth, from the initial to the adult. 
Barrandeoceras Sternbergi, Barrande, sp. 
1854. Ncmtilns Sternbergi, Barrande, Leonard & Bronn’s Jalirbuch, 
Heft i. p. 6. 
1867. Nautilus Sternbergi, Barrande, Syst. Sil. de la Bohenie, vol. ii. 
pt. i. p. 147, pi. xxxvi., pi. xxxvii., pi. xli. 
1883. Barrandeoceras Sternbergi, Hyatt, “ Genera of Fossil Cepha- 
lopods,” Proc. Boston Soc. Nat. Hist. vol. xxii. p. 290. 
Sp. Char. The shell is discoid and flattened, like its congeners, 
with from three to four volutions, whose breadth is to their thick- 
ness as 3 : 2. They are all exposed, as there is no overlapping. There 
is a central vacuity. The transverse section is elliptical, the ratio 
of the two diameters being as 3 : 2. That end of the ellipse corre- 
sponding to the concave side of the shell is rounded like the other 
end, owing to the whorls not in the least overlapping. The increase 
in breadth of the last whorl is in the ratio of 1 : 3, and the thickness 
varies as 3:8 in the same length. The body-chamber occupies 
about half of the last whorl. The aperture lies apparently in the 
plane of the last septum, but it is imperfect in all the specimens 
examined. The distance of the septa in the middle of the sides of 
the shell in the largest specimens is equal to L of the ventro-dorsal 
diameter ; their convexity amounts to ^ of the same. The sutures 
form a shallow sinus upon the sides of the shell, and arch upwards 
towards the periphery. The siphuncle is situated a little above the 
centre. The test is ornamented only with very fine transverse lines 
of growth, so that it appears quite smooth when looked at with the 
naked eye. 
