. Bulletin - New York State Museum. Science. 498 NEW YORK STATE MUSEUM depressed elliptic, the ratio of the dorsoventral diameter to the trans- verse one as 8 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).
. Bulletin - New York State Museum. Science. 498 NEW YORK STATE MUSEUM depressed elliptic, the ratio of the dorsoventral diameter to the trans- verse one as 8 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
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectscience, bookyear1887
