SiilS PALJEONTOLOGY OF NEW-TOEK. 



280. 12. ENDOCERAS ANGUSTICAMERATUxM (n. 5J5.). 



Pl. LI. Fig. 3. 



Teretely cylindrical, very gradually tapering ; septa distant about one sixth the diameter 

 of the shell ; outer chamber deep ; siphuncle excentric? 



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 tiie 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 («.:?;>.). 



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 fran-ment, showing several of the chambers, with the large siphuncle projecting above. 



Fi"'. 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 soinewhat 

 irregubr in this respect. 



FJ"'. 1 c. A transverse section of the larger e.xtremity, which is worn off 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 and locality. In the higher part of the Trenton limestone near Middleville. 

 282. 14. ENDOCERAS MAGNIVENTRUM ? 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. 



