40 
NAFTILOTDEA. 
half a line. The test in some specimens retains its natural colour 
in the shape of red longitudinal, irregular bands, which follow the 
course of the volutions up to the border of the aperture. The 
breadth of these hands, at the base of the hody-chamher, is about 
half a line, and they are separated by a similar space of a whitish 
colour. 
Remarks. The species most nearly allied to T. pulckrum are 
(1) T.amicum{^y&i. Sil. Boh. pis. xv., xxviii.), which has, however, 
more contiguous whorls, not so central a siphuncle, and the annu- 
lations covering the whole surface of the body-chamber ; and (2) T. 
asperum (pi. xvi.), in which the body-chamber is straightened after 
freeing itself from the septate part of the shell, the siphuncle is 
farther from the centre, and the annulations cover the entire surface 
of the septate part of the shell, including nearly the whole of the 
body-chamber. 
Horizon. Etage E ( = Salopian). 
Locality. Butowitz, Bohemia. 
Well represented in the Collection. 
Trochoceras Americanmn ?, Billings. 
1857. Gyroceras (^Lituites) Americanmn^ Billings, Geol. Surv. Canada, 
Eep. of Progress for the years 1853-1856, p. 309. 
Rp. Char. “ Tube long, slender, gradually tapering ; section 
semi-elliptical ; dorsal aspect nearly flat ; side and ventral aspect 
convex, and ornamented with prominent annulations, which, in 
leaving the lateral angles, are at first deflected towards the aperture 
at a sharp angle, and then curved towards the apex, crossing the 
ventral side nearly at right angles to the length, or with but a 
slight undulation towards the apex. The annulations are upon the 
average five lines and a half distant from the summit of one ridge 
to that of the next, the intervening spaces being regularly convex 
[? concave] ; the surface is further marked by coarse striae following 
the curves of the lateral and dorsal annulations ; on the flat dorsal 
surface, where these latter do not appear, the striae curve in the 
direction of the smaller extremity of the fossil. The dorso-ventral 
and lateral diameters appear to be about equal in the fragments 
examined, which are, however, somewhat distorted : the siphuncle 
is small and slightly eccentric, being nearest the dorsal aspect ; the 
septa are convex and distant four lines. 
“ The length of the longest fragment measured along the outside 
curve is twelve inches, its ^greatest diameter one inch and a half, and 
the least one inch, thus tapering at the rate of about half a line to 
the inch ; %t least one third of the outer whorl remains, and shows 
