36 
NAUTILOIDEA. 
Remarks, The sculpture in the present species is very similar to 
that of T, Sandhergeri, Barr., hut it differs in other respects, as 
already pointed out. A specimen in the Collection from the AVenlock 
of England, which exhibits no tendency to asymmetry, is somewhat 
doubtfully referred to this species, on account of its coarse ribbing ; 
it is a cast. 
Horizon. Etage E (= Salopian) ; Wenlock Limestone. 
Localities. British. West of England ? — Foreign. Lochkow, 
Kosorz, Bohemia. 
Well represented in the Collection. 
Trochoceras nodosum, Barrande. 
1848. Trochoceras nodosum^ Barrande, in Haidinger’s Berichte iiberdie 
Mittheil. von Freund, der Naturwiss. in Wien, Band iv. p. 208. 
1867. Trochoceras nodosum, Barrande, Syst. Sil. de la Boheme, vol. ii. 
pt. i. p. 110, pi. XXV. ff. 7-18. 
Sp. Char. Shell with two whorls, which are contiguous excepting 
for a very short distance near the aperture. The want of symmetry 
is quite perceptible. The enrolment is sinistral. The transverse 
section is subquadrate, the ventro-dorsal slightly exceeding the 
transverse diameter. The rate of increase is rapid, the shell in- 
creasing its diameter about three times in the last volution. The 
body-chamber occupies about half the length of the external whorl, 
and has a slight sinus on the convex border. The septa are about 
i the shell-diameter apart. The siphuncle is placed about midway 
between the centre and the convex border. The ornaments consist 
of slight oblique annulations which are developed chiefly on the sides 
of the shell, scarcely at all on the concave border, and terminating 
at the edge of the convex side in a nodule or small elongated pro- 
tuberance. The surface of the test is ornamented with a network of 
subregular raised lines. The longitudinal lines which are the 
stronger are about ^ a line apart, upon the body-chamber, while 
from 3 to 4 of the transverse lines can he counted within that space. 
The surface of the cast of the body-chamber is covered with epi- 
dermids, which are sometimes visible to the naked eye. 
Remarks. The ornaments of T. nodosum distinguish it from those 
species which in other respects resemble it. Professor Hyatt points 
out that in many of the characters of this species, such as the flat- 
tened sides and periphery, and the aperture, it resembles Barrandeo- 
ceras, q. v. 
Horizon. Etage E ( = Salopian). 
Localities. Dworetz, Lochkow, Bohemia. 
