16 
NATJTILOIDEA. 
Trochoceras ? serpens ’ belongs in all probability to some other genus ; 
it is only a fragment. 
BemarTcs. By a singular coincidence Professor Hall, some years 
after Barrande’s description of Trochoceras in Haidinger’s ‘ Berichte ’ 
(1847), described certain forms from the Devonian rocks of North 
America (Pal. New York (1852), vol. ii.) and gave them the same 
generic name. There is, however, no question of priority involved, 
as Barrande’s publication of the genus preceded that of Hall by 
nearly five years. 
It may be added that Barrande divided Trochoceras into 2 series, 
Exogastric and Endogastric ; but the latter is represented by only 
one species in Bohemia, and none in Britain. He also separated 
the annulated from the smooth forms, &c. 
a. Species without annulations. 
Trochoceras lamellosum, Hisinger, sp. 
1837. Lituites lamellosus, Hisinger, Letli£ea Svecica, p. 28, tab. viii. f. 7. 
1849. Lituites lamellosus, d’Orbigny,Trodr. de Paleont. Stratigr. vol. i. 
p. 27. 
\_Not 1880. Discoceras lamellosum, Angelin & Lindstrom, Fragmenta 
Silurica, p. 10, pi. ix. f. 12, pi. x. ff. 3-5, pi. xv. f. 30.] 
Sp. Char?" The portion of the shell known, which is all septate, 
consists of about 2 whorls, in which no asymmetry can be seen. 
The section is transversely elliptical, the ratio of the two diameters 
being as 12 : 17. The whorl increases its diameter about 2| times 
in a volution. The septa are very approximate, their distance very 
slowly increasing with the growth of the shell ; they are about 
1 line apart where the diameter of the shell is 8 lines, and nearly 
2 lines apart where the shell-diameter has increased to 10 lines. 
These measurements are taken upon the sides of the shell. The 
siphuncle lies between the centre and the ventral side. The orna- 
ments consist of fine transverse striae, annulations being entirely 
absent. 
JRemarhs. There is a discrepancy between the figures of this 
species in the ‘ Fragmenta Silurica ’ and Hisinger’s original figure in 
Die Versteinerungen des Rheinischen Scliichtensystems in Nassau, 1856, 
p. 175, tab. XV. f. 1. 
^ The following is Hisinger’s description : — “ Lituites lamellosus testa dis- 
coidea ; anfractibus contiguis, rotundatis dorso applanatis, ultimo . . . . ; septis 
numerosissimis ; siphone dorsali.” 
