PLATE XXIV 
Figs. 1-5, Cameroceras trentonense Hall. 1, 2A, lateral views showing 
siphuncle. 2B, ventral view of 2A. 3, cast of interior of siphuncle and 
endocone; compare with 5. 4, lateral view, exposing one segment of the 
siphuncle. 5, endocone, thickened interiorly by a calcareous deposit, lighter 
in color, contrasting with the darker color of the matrix filling the interior 
of the endocone. 1, 2, from Middleville, New York; No. 815 in American 
Museum of Natural History; originals of Pal. New York, vol. 1, 1847, pi. 
56, figs. 4 a, b, c. 3, 4, from Multona brook, 2 miles northeast of Middle- 
ville, New York; No. 59449, in the U. S. National Museum. 5, from Poland, 
in Herkimer, New York; No. 59450, in the U. S. National Museum. All 
specimens from the Trenton limestone. 
Figs. 6 A-E'. Cameroceras calumettense Foerste. A lateral view; B, view 
of same specimen, facing the interior of the conch. C, ventral side of an- 
other specimen. D, E, opposite sides of an endocone split so as to show the 
thicknened inner walls of the endocone, but omitting the deposit of matrix 
which filled its interior. At the base of the specimen, the axial part of the 
calcareous deposit is occupied by a thin transverse band, scarcely 1 mm. in 
width. From Little Calumet creek, 6 miles south of Louisiana, Missouri. 
In the U, S. National Museum. 
