ORTHOCEKATIDJi. 
81 
Orthoceras gracile, Blumenbach. 
1803. Orthocei'atites gracilis, Blumenbacli^ Specimen Arcbaeologiae Tel- 
luris, p. 21, tab. ii. f. 6. 
? 1842. Orthoceratites gracilis, d’Archiac & de Verneuil, Trans. Geol. 
Soc. 2nd ser. vol. \i. pt. ii. p. 344, pi. xxvii. f. 4. 
Sj?. Char. Shell straight, very elongated. Section circular. Kate 
of tapering very gradual, about 1 in 24. Septa numerous, hori- 
zontal. Siphuncle small, cylindrical, nearly marginal. Test’ 
unknown. 
Remarlcs. This species differs from 0. longicameratum in the num- 
ber of its septa, which is at least double, and in the position of its 
siphuncle. 
The specimen figured by Blumenbach must have been partially 
decomposed, as it is represented with considerable spaces at the 
sutures, so as to expose the siphuncle to view. It was pyritized, 
as are all the Orthoceratites in the Wissenbach slates. 
I am not satisfied about this being the species figured and de- 
scribed by MAT. d’Archiac and de Terneuil. Their shell has a much 
more rapid rate of tapering than Blumenbach’s. It is stated to be 
very common at Wissenbach. 
Horizon. Orthoceratiten-Schiefer ; Lower Devonian. 
Locality. Wissenbach, near Dillenburg, Nassau. 
Well represented in the Collection. 
Ortboceras crassum, F. A. Koemer. 
1843. Oi'thoceratites crassm, F. A. Koemer, Die Verstein. des IJarzge- 
birges, p. 35, tab. x. f. 6. 
1854. Orthoceras crassum, F. A. Koemer, Palaeootographica, Band iii. 
p. 110, Taf. xi. f. 23, a-b. 
1856. Orthoceras crassum, G. & F. Sandberger, Die Verstein. Nassau, 
p. 164, Taf. xix. ff. 1, \a. 
1870. Orthoceras crassum, Tietze, Ueber die devonischen Schichten 
von Ebersdorf, p. 36, Taf. i. f. 17. 
1884. Orthoceras crassum, Kayser, Die Orthoceras-schiefer, &c., in 
Jahrb. d. konigl. preussisch. geolog. Landesanst. u. Bergak. zu 
Berlin f. d. Jahr 1883, p. 15. 
Sp. Char. Shell straight, very long. Section cylindrical. Kate 
of tapering 1 in 8. Septa distant about 5 the diameter of the shell, 
very convex. Siphuncle central, rather thick. Surface ornamented 
with fine transverse lines. 
Horizon. Spiriferen-Sandstein ; Orthoceratiten-Schiefer ; Lower 
Devonian. 
G 
