EXDOCERATID^. 
147 
1857. Orthoceras vaginatum, Boll, Beitrag ziir Kenntniss der Silur. 
Ceph., in Arcliiv fiir die Xaturkunde von Mecklenburg, p. 9, Taf. i. 
ff. 1 a, 1 h. 
18Gl3. Endoceras {Orthoceras) trochleare, Barrande, Syst. Sil. de la 
Boheme, vol. ii. Texte iii. 1874, p. 710, pi. ccxxxviii. ff. 12, 13, 
pi. ccccxli. ff. 25, 26. 
? 1809. Orthoceras trochleare, Karsten, Die Verstein. des Uebergangs- 
gebirges in den Gerollen der Herzogtbiimer Schleswig und Holstein, 
p. 50, Taf. x\4i. f . 7 « (not f. 7 5). 
1873. Orthoceras vaginatum, Malaise, Terrain Silurieu dii centre de la 
Belgique, p. 89, Tab. iv. f. 1. 
1880. Orthoceras vaginatum, Angelin-Lindstrom, Fragui. Silurica, p. 2, 
Tab. vii. ff. 4-7, 11-12, ? 1-3. 
? 1882. Orthoceras {Endoceras) vaginatum, Blake, British Foss. Ceph. 
pt. i. p. 164. 
Fi'j. 15. 
Fig. 16. 
Fig. 1.5. Endoceras troch'eare . — Fragment showing the sculpture of the test; 
natural size. 
Fig. 16. Var. ‘percostatum . — Fragment showing the coarser sculpture of the 
test as compared with the preceding ; natural size. 
Bp. Char. Shell straight or slightly curved. Section circular. 
Rate of increase varying from 1 in 12 to 1 in 9. Length of the 
body-chamber about three times the diameter of the last chamber ; 
slightly constricted near the aperture. Septa approximate, that is 
from 2 to 3 lines distant, where the shell has a diameter of 1| inch. 
Siphuncle marginal, its diameter about that of the shell. Prin- 
cipal ornaments consisting of close-set, low, undulating annulations, 
varying someAvhat in size and prominence in different parts of the 
shell, and becoming almost obsolete in adult individuals. The 
