218 
PALAEONTOLOGY OF NEW-YORK. 
280. 12. ENDOCERAS ANGUSTICAMERATUM (n. sp.). 
Pl. LI. Fig. 3. 
Teretely cylindrical, very gradually tapering ; septa distant about one sixth the diameter 
of the shell ; outer chamber deep ; siphuncle excentric 1 
The specimen is a fragment somewhat compressed, giving a greater breadth in the figure 
than the actual diameter. The outer chamber contains a small tube, which is too obscure 
to determine satisfactorily its character, though indicating that the species belongs to the 
Genus Endoceras. The siphuncle of this specimen cannot be satisfactorily examined, 
and therefore I have some hesitation as to the true character of the fossil. The specimen is 
denuded of the shell, so that the surface markings are unknown. 
Position and locality. This species is found in the higher part of the Trenton limestone 
at Middleville. 
281. 13. ENDOCERAS MAGNIVENTRUM (n. sp.). 
Pl. LIII. Figs. 1 a, b, c, d, e. 
Elongated, very gradually tapering ; siphuncle very large, occupying about three fifths 
the diameter of the shell ; septa extremely convex, distant one eighth the diameter of the 
shell. 
The specimen figured is a fragment of an individual, which, when perfect, could not 
have been less than six feet in length. The septa are more convex than in any other species 
known to me, being in this respect slightly irregular as shown in the figure. The siphuncle 
is proportionally larger, and the septa more approximate than in any other species described. 
Fig. 1 a. A fragment, showing several of the chambers, with the large siphuncle projecting above. 
Fig. 1 b. An artificial longitudinal section, showing the proportional diameter of the siphuncle and shell, 
as well as the extreme convexity of the septa, which are correctly represented as somewhat 
irregular in this respect. 
Fig. 1 c. A transverse section of the larger extremity, which is worn oil’ obliquely. At d d the outer 
line indicates the edge of the siphuncle, the inner one being perhaps an exfoliation from the 
same, but too obscure to determine its character. At e , the embryo tube, with a young shell, 
is clearly distinguishable within the siphuncle. The position of the same is shown in the 
longitudinal section, which slightly cuts its outer edge. The small size of the embryo tube 
indicates that this section is distant from the outer chamber, at which point this tube usually 
fills the siphuncle. 
Position arid locality. In the higher part of the Trenton limestone near Middleville. 
282. 14. ENDOCERAS MAGNIVENTRUM 1 var. 
Pl. LIV. Fig. 2 b. 
This specimen consists of a portion of an extremely large siphuncle, with a few septa 
attached. The septa are equally convex with those of the specimen figured on Plate LIII; 
but their distance is equal or greater, though the diameter of the siphuncle is less. 
Position and locality. Same with the preceding. 
