36 
IfATTTILOrDEA. 
dudes within one of its borders the axis of the shell. The surface 
is ornamented with very fine transverse striae, which appear to 
have a direct imbrication. They are separated by very slight 
horizontal depressions. 
Horizon. Etage E, bande e 2 ( = Salopian). 
Locality. Lochkow, Bohemia. 
Represented by two fairly good specimens. 
Orthoceras pastinacea, Barrande. 
1868. Orthoceras pastinacea, Barrande, Syst. Sil. de la Boheme, vol. ii. 
Texte iii. 1874, p. 98, pi. ccxlviii. ff. 4-8, pi. cccxxx. ft. 8-10. 
/8p. Char. Shell always a little curved. Section circular, when 
not abnormally compressed. Rate of increase about 1 in 4. Body- 
chamber highly developed, occupying nearly half the length of the 
shell, its length being about 3 times the diameter of its base. 
Owing to the rapid increase in the diameter of the shell, the body- 
chamber has a volume more than double that of the septate portion. 
The septa have an obliquity of about 5°, corresponding with that of 
the aperture ; they are distant from about | to J- the diameter, 
according to the growth of the shell. The siphuncle is central. 
The test is almost always wanting, having been dissolved away ; 
but some fragments show subregular transverse striae, having a 
direct imbrication. 
Horizon. Etage G, bande g 3 (=Downtonian). 
Locality. Hlubocep, Bohemia. 
Well represented in the Collection. 
Orthoceras rivale, Barrande. 
1866. Orthoceras rivale, Barrande, Syst. Sil. de la Boheme, vol. ii, 
Texte iii. 1874, p. 383, pi. ccix. IF. 1-7, pi. ccxvi. ff. 4-10, 
pi. ccclxxiv. ff. 1-7, pi. ccclxxxvii. ff. 1-3, pi. ccccvi. ff. 1-4. 
Sjy. Char. Section circular. Rate of increase about 1 in 11. 
Septa distant about ^ the diameter. The organic deposit is well 
developed. Body-chamber unknown. Siphuncle very eccentric, 
the edge of the siphuncle touching the centre. Surface ornamented 
with subregular strise, the surface between which appears to be 
quite smooth. 
Horizon. Etage E, bande « 2 ( = Salopian). 
Localities. Lochkow, Blauha Hora, Bohemia ; Feuguerolles (Cal- 
vados), France, 
