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NEW YORK STATE MUSEUM 



depressed elliptic, the ratio of the dorsoventral diameter to the trans- 

 verse one as 8 -.g in the earlier and later parts of the conch. The 

 conch is strongly curved and may have approached the gyroceraconic 

 condition ; an inner arc of 50 mm has a hight of 8 mm. 



The living chamber attains apparently about one third the length 

 of the total conch. The aperture is not contracted, the margin nearly 

 straight. The growth lines indicate that the hyponomic sinus is 

 shallow and situated on the arched external side (exogastric shell). 

 The cameras are shallow (6 to 8 in the space of 10 mm) ; the sutures 

 straight transverse with a faint lobe on the ventral side, the septa 

 very concave, their depth twice that of the cameras. 



The siphuncle is small, its width 

 one eighth the diameter of the shell ; 

 nummuloidal, propioventran in po- 

 sition. The septal necks are bent 

 outward and developed on the dor- 

 sal side only ; thereby giving the 

 siphtmcular segments an asymme- 

 tric section. The surface is smooth. 

 Position and localities. Fre- 

 quent in the dove-colored limestone 

 (Chazy Q) of Isle La Motte and 

 also occurring in the same horizon 

 at Valcour island. 



Observations. In the characters 

 and position of the siphuncle, nota- 

 bly in the restriction of the develop- 

 ment of the curved septal necks to 

 the dorsal side, this species is a typi- 

 cal member of the Ooceratidae and 

 specially of Ooceras, wherewith it 

 also has in common the close septa- 

 tion and the rapid rising of the 

 septa on the ventral side. A differ- 

 ence of as yet unknown importance 

 appears to lie in the direction of the 

 compression of the conch; the shell of Ooceras being compressed 

 and that of this species depressed. This depressed section may sug- 

 gest a closer relationship to the original Cyrtoceras Goldfuss, than to 

 Ooceras. 



A form which in the longitudinal section as also in its curvature, 

 rate of growth, position and character of the siphuncle bears a 



Fig. 52 Ooceras 

 sp. nov. Longitudinal 

 Natural size. 



ativent. rum 

 section. 



