270 
AUG. F. FOERSTE 
6. Protocycloceras whitfieldi Ruedemann 
Plate XXXIII, fig, 4 
Orthoceras bilineatum, Whitfield, Bull. Amer. Mus. Nat. 
Hist., 3, 1890, p. 35, pi. 2, fig. 5, fig. 17 a, b, 
Protocycloceras whitfieldi Ruedemann, Bull. New York 
State Mus. Nat. Hist., 90, 1906, p. 443, fig. 17a, pi. 15, fig. 7. 
In a specimen of Protocycloceras whitfieldi Ruedemann, from 
the Fort Cassin beds at Fort Cassin, Vermont, the structure of 
the siphuncle is more distinctly shown. At the septal neck of 
the funnel, the latter bends abruptly downward; the funnel 
contracts downward in one specimen from a diameter of 7 mm. 
at the neck to 6.3 mm. a little below the middle of the camera 
beneath, expanding to 6.5 mm. at its lower margin, which de- 
scends for a distance equalling about one-fourth of the height of 
a camera into the upper part of the funnel next beneath. In 
longitudinal sections, the siphuncle appears broadly annulated 
at the septa, with very shallow intermediate grooves which have 
their maxima of contraction slightly beneath mid-height of the 
camerae. No distinct markings were noticed on the surface 
of either Protocycloceras whitfieldi or of Protocycloceras lamarcki, 
7. Protocycloceras cf. lamarcki (Billings) 
Plate XXVII, fig. 5; Plate XXXIII, fig. 5A, B 
Orthoceras ? sp., Holtedahl, Paleozoic Series of Bear Island, 
1919, p. 129, pi. 13, fig. 1. 
Conch enlarging very slowly, from 13.3 mm. to 14.6 mm. in 
a length of 18 mm. The lower 4 camerae occupy a length of 10 
mm.; and the upper 5 camerae, of 14 mm. The sutures are 
assumed to have been directly transverse though they are not 
exposed for a sufficient distance around the circumference of the 
conch to permit the determination of their course with exact- 
ness. The septa are moderately concave, curving downward 
a distance of 2 mm. where their diameter is 14 mm. The siph- 
uncle is relatively large, being 5 mm. in diameter where the 
diameter of the conch is 14.5 mm. The position of the siphuncle 
