112 . NEW YORK STATE MUSEUM 



The type specimen (plate 7, figure 12) measures 13.5 mm in 

 length and 4 mm in width. It shows a distinct, very concave septum 

 in the apical portion. Our specimens are so flattened that their 

 section can not be conclusively determined. It seems to have been 

 elliptical with one side angular. 



Orthoceras arcuolineatum nov. 

 PL 8, fig. I, 2 



Slender, small orthoceracone, increasing at the rate of .5 mm of 

 diameter in length of 10 mm. Section elliptic, nearly circular, the 

 minor and major diameters as 7.1 to 7.5 mm. Camerae shallow, 

 nearly four times as wide as deep. Septa closely arranged, about 2 

 mm apart where the diameter of the conch is 7 mm deep, their 

 depth approximately corresponding to that of the camerae. Sutures 

 arching slightly up on one side. Living chamber not known. 

 Siphuncle centren, small, about one-seventh the diameter of the 

 conch ; segments cylindrical, the fimnels short and straight. Orna- 

 mentation consisting of relatively widely separated (about 2 in i 

 mm) sharp raised transverse lines, or ridges, which are inter- 

 sected by extremely fine longitudinal lines. The transverse lines 

 are strongly bent upward on one of the narrow sides of the conch. 



Horizon and locality. Canajoharie shale at Ford Edward, N. Y. 



Remarks. This species is based on only .the small fragment that 

 is figured here. This shows, however, especially in the ornamenta- 

 tion, characters that distinguish it from other Trenton species known 

 to us. It is apparently, from the character of the siphuncle, a true 

 Orthoceras. 



Orthoceras hudsonicum nov. 



PI. 8, fig. 3-10 



Small to medium sized, slender, slightly curved cone, with closely 

 arranged septa and subcentral, narrow siphuncle. The cone widens 

 so gradually that in a distance of 50 mm it expands from 5 mm to 

 10 mm or less (measured in compressed specimen). The septa equal 

 in depth the chambers ; they are closely arranged, about 2 mm apart, 

 where the conch is 7 mm wide ; the sutures are straight transverse. 

 The siphuncle is centren, wide, about one-third the width of the 

 conch, the funnels apparently short and straight. The living cham- 

 ber and aperture have not been observed. The nepionic conch 

 possesses only fine longitudinal striae, of somewhat irregular char- 



