BEEKMANTOWN AND CHAZY FORMATIONS OF CHAMPLAIN BASIN 497 



the section slightly compressed oval with very little difference be- 

 tween the minor and major diameters (14 and 15 mm in one speci- 

 men) ; the ventral side being a little narrower than the dorsal. The 

 largest diameter observed is about 40 mm at the base of the living 

 chamber; the curvature is strong, an arc of 35 mm having a hight 

 of 4 mm. 



Only the base of the living chamber has been observed and the 

 apical part of the conch is missing. The cameras are very shallow, 

 there being 4 of them in the space of 10 mm ; they are curved, 

 strongly arching forward on the convex (ventral ?) 

 side ; the sutures nearly straight transverse with a 

 broad lobe on the convex side ; the septa flat (their 1 

 depth is about iy 2 that of the cameras) and bend- 

 ing orad on the ventral side. 



The siphuncle is large, strongly nummuloidal, Fi s g e ^ ly f °p e no a v ! 

 expanding to twice its width (one eighth the width ^"Natural SX 

 of the shell) in the cameras. Septal neck only 

 present on dorsal side ; the interseptal segments, which are of disk- 

 like shape, marginal in position on the convex side of the conch. 



Position and localities. In the dove-colored limestone 

 (Chazy Q) of Isle La Motte, and of the outcrops north of the road 

 to Little Monty bay south of Chazy village. One specimen was col- 

 lected by Professor Hudson in the lower Chazy of the neighbor- 

 hood of the normal school at Plattsburg N. Y., where it is asso- 

 cited with Rhynchonella acuticostris, Scalites 

 angulatus, Harpes antiquatus, etc. 



Observations. The most striking characters of this species, 

 which is a typical Ooceras, are found in the structure of the si- 

 phuncle and the section of the conch. In the siphuncle the septal 

 necks are absent on the ventral (outer) side [see fig. 11], but 

 strongly developed on the dorsal side where they are bent outward 

 and hooklike in section. This is one of the diagnostic features of 

 the Ooceratidae. 



Ooceras (?) lativentrum sp. nov. 



Plate 35, figure 7-10 



Description. Slender, medium sized cyrtoceracone. The 

 largest specimen observed, which lacks aperture and apical part, 

 measures 90 mm, and may have attained twice that size when com- 

 plete. The largest aperture has a diameter of 31 mm. The rate of 

 growth is 1 mm in 6 mm in the dorsoventral plane. The section is 



