38 
NATJTILOIDEA. 
Trochoceras degener, Barrande. 
1848. Trochoceras degener, Barrande, in Haidinger’s Berichte iiber die 
Mittheil. von Freund, der Naturwiss. in Wien, Band iv. p. 208. 
1867. Trochoceras degener, Barrande, Syst. Sil. de la Bolieme, vol. ii. 
pt. i. p. 121, pi. xxviii. ff. 15-21. 
^'p. Char. This species has never been found with the coiled part 
complete, but in examples from which the matrix has been removed 
a slight amount of asymmetry is observable. The section is sub- 
quadrate, the ventro-dorsal diameter slightly exceeding the trans- 
verse. The shell increases its diameter about three times in half a 
whorl. The body-chamber occupies about half of the total length 
of the fossil. The aperture is a little oblique. The septa are distant 
from each other about the diameter. The siphuncle is situated 
about midway between the centre and the convex side ; its elements 
are cylindrical. The surface is ornamented with rather low, rounded 
annulations, of slight obliquity, which form a shallow sinus on the 
convex side. The whole of the test is covered with a network of 
very fine and regular lines ; the longitudinal, which are the stronger, 
are less than half a line distant from each other, the transverse lines 
are about three times as numerous as the former. 
Remarhs. Trochoceras cequistriatum, Barr. (pi. xxix.), resembles 
the present species in its general form and ornaments, but the ribs 
are obsolete upon the body-chamber, and the siphuncle is differently 
placed. The finer ornaments of T. degener are repeated in several 
species, such as T. Sandhergeri, T. trochoides, &c. 
Horizon. Etage E ( = Salopian). 
Locality. Lochkow, Bohemia. 
Well represented in the Collection. 
Trochoceras disjunctum, Barrande. 
1867. Trochoceras disjunctum, Barrande, Syst. Sil. de la Boheme, 
vol. ii. pt. i. p. 122, pi. xxii. ff. 2-7. 
Sp. Char. The shell never attains a complete volution, but when 
the initial point is preserved it is not far short of one. The 
asymmetry is very slight. The transverse section is nearly circular. 
The shell increases its diameter nearly four times in the course of 
a volution. The body-chamber occupies about half the length of 
the entire shell. The aperture, whose plane is oblique to the long 
axis of the shell, is slightly sinuated on the ventral border. The 
septa are distant about ^ the shell-diameter, and their convexity 
is also about \ of the same. The siphuncle is situated about mid- 
