62 
NAUTILOIDEA. 
regularly disposed and close-set. Longitudinal striae are also observ- 
able, and these when very strongly marked have led to the separation 
of a varietal form (0. ccelebs) from the main group. 
RemarJcs. This species is closely allied to 0. Hisingeri, Boll, as 
pointed out by Barrande, but the latter has a more robust habit, 
and the ribs are sharper, more prominent, and wider apart than they 
are in 0. dulce. According to M. Barrande, 0. Hisingeri lessens in 
its diameter towards the aperture, which 0. dulce does not do. 
Horizon. Etage E, bande e2 (= Salopian). 
Localities. Lochkow, Dlauha Hora, Wiskocilka, Bohemia. 
Well represented in the Collection. 
Yar. omega, Barrande. 
1868. Oi'thoceras dulce, Barrande, var. omega, Barr. Syst. Sil. de la 
Boheme, vol. ii. Texte iii. 1874 (janvier),p. 321, pi. ccxciv. ff. 1-3. 
1878. Oi'thoceras dulce (?), Kayser, Abhandl. zur geologisch. Special- 
karte von Preussen, Band ii. Heft 4, p. 78, Taf. xx. ff. 17, 17 a. 
This variety is remarkable for the finely crenulated character of 
its transverse lines. In this it resembles 0. Hisiiujeri, but the striae 
are much closer together and more strongly crenulated than they 
are in that species. In other characters there is nothing to separate 
this variety from 0. dulce. 
I think there can be little doubt that Kayser’s form is identical 
with the present one. He describes it as having crowded, wavy, 
lamellose, transverse striae, which ho figures. His specimen is a 
fragment, partly buried in the matrix. 
Horizon. Etage E, bande e 2 ( = Salopian). 
Localities, Karlstein, Dworetz, Bohemia. 
Orthoceras pseudo-calamiteum, Barrande. 
1852. Orthoceratites pseudo-calamiteus, Q.iienstedt, Handb. der Petre- 
faktenkunde, p. 342, tab. xxvi. f. 8. 
1868. Orthoceras pseudo-calamiteum, Barrande, Syst. Sil. de la Boheme, 
vol. ii. Texte iii. 1874 (janvier), p. 261, pi. ccxvii. f. 8, pi. ccxxii. 
ff. 11, 12, pi. cclxxviii., pi. ccLxxxvi. ff. 11-16, pi. ccclxi. ff. 15-17. 
Sp. Char. Shell straight. Section circular. Bate of increase 
very slow ; about 1 in 24. Body-chamber imperfectly known. 
Distance between the septa slowly and regularly increasing to a 
maximum of 4- the diameter. Siphuncle central. Ornaments of the 
surface consisting primarily of prominent and regularly disposed 
horizontal annulations, eacb corresponding to one of the air-chambers. 
The spaces sepa^’ating the annulations are concave and wider than 
the rings. The annulations are distant about the diameter, but 
this distance increases in adult specimens to nearly Acute and 
very prominent lamellose ribleta run longitudinally throughout the 
