TKOCHOCERATIDJE. 
23 
are nummuloidal. The test is ornamented only with fine stride of 
growth. 
Remarks. Trochoceras secula and T. mexpectatiun^ Barr. (Syst. 
Sil. de la Boheme, 1877, vol. ii. pt. i., Supplem. efc Serie tardive, 
p. 87, pi. ccccxci.), are the only species of Trochoceras in which the 
siphuncle is endogastric. There appears to be nothing to distin- 
guish these two species from Meloceras^., save their want of symmetry 
and greater curvatnre. 
Horizon. Etage E ( = Salopian). 
Locality. Lochkow, Bohemia. 
Represented in the Collection by two examples. 
Trochoceras boreale^ Eoord. 
Sp. Char. Shell discoid, compressed, whorls in contact, about 
three in number, all exposed. Section elliptical, the ratio of the 
two diameters about as 6 : 8 ; siphuncle between the centre and the 
convex side. Septa approximate; two lines apart on the sides, 
where the shell has a diameter of 11 lines, increasing to 2| lines 
where the diameter is 1^ inches. Body-chamber and test unknown. 
There are no indications of ribbing or of any other ornaments upon 
the cast. 
Remarks. This is a much larger species than any of those of the 
Niagara rocks of North America that come at aU near to it. Tro- 
choceras TEneas., HalP, agrees with it in the distance of the septa 
and position of the siphuncle, but the section is different, and there 
are marks of very distinct annulations upon the cast. Salter^ 
described, amongst other Arctic Silurian fossils, one which he 
called “ Lituites , n. sp. ; ” but this is stated to have six or 
seven whorls at least, and therefore it could have no affinity with 
the present species. There was, therefore, no other course but to 
give this form a new name. 
Honzon. Silurian. 
Locality. Wellington Channel, Arctic America. 
Represented in the Collection by one example, collected by Captain 
Inglefield. 
* See Part I. of this Catalogue, p. 269. 
^ 20th Ann. Keg. Kep. of the Uuiv. of the State of New York, revised edition, 
1870, footnote explanation of plate xxv. f. 16. 
3 Journal of a Voyage in Baffin’s Bay and Barrow Straits in the years 1850- 
1851, by Dr. P. C. Sutherland (1852), Appendix, p. cexxii. 
