. Annual report of the Regents. New York State Museum; Science. chamber lodges the animal. The septa are pierced by a correspond- ing series of holes, the walls of which are often prolonged backward or forward into siphonal funnels, the whole constituting the siphuncle. In the Nautiloidea, the sutures are, as a rule, simple or but slightly lobed, and the siphuncle is commonly central or eccentric, but seldom marginal, with the funnels generally di- rected backward. The 'embryonic shell, or proto- conch, is rarely retained. The shells of cephalopods are either straight (more or less conic) or v
. Annual report of the Regents. New York State Museum; Science. chamber lodges the animal. The septa are pierced by a correspond- ing series of holes, the walls of which are often prolonged backward or forward into siphonal funnels, the whole constituting the siphuncle. In the Nautiloidea, the sutures are, as a rule, simple or but slightly lobed, and the siphuncle is commonly central or eccentric, but seldom marginal, with the funnels generally di- rected backward. The 'embryonic shell, or proto- conch, is rarely retained. The shells of cephalopods are either straight (more or less conic) or variously curved and coiled to close involution. NAUTILOIDEA Genus orthoceras Breyn [Ety.: 6f>06^, straight; z£7>«9, horn] (1732. Dissert at io pJiysica de polythalamiis) Fig. 146 Orthoceras Shell a Straight conic tube, with a large body muitiseptum chamber and numerous air chambers, separated by convex septa. Sutures simple, at right angles to the long axis of the shell; siphuncle central, sub- central, or eccentric, cylindric or sometimes widening in the chambers. Surface smooth or variously ornamented by transverse or longitud- inal striae, or by annulations. Orthoceras muitiseptum Hall (Fig. 146) (1852. Pal N. Y. 2:14, pi. 4 (bis)) Distinguishing characters. Cylindric, gradually tapering; septa distant one sixth to one seventh the diameter. Found in the upper Medina sandstone at Lock- port, etc. (Hall). Probably also at Niagara. Orthoceras annulatum Sowerby (Fig. 147). Orthoceras undulatum Hall (1852. Pal N. Y. 2:293, pi. 64, 65) Distinguishing characters. Strong annulations;. moderately strong longitudinal lines which node ^J^^-^. 147 Orthof eras an- nulatum. Terminal por- , . r- . • 11- lion siiowing sliellof liv- the annulations, fine transverse striae; elliptic ingciiamberand section- ed camerae (aft3r Bar- cross-section; subcentral siphuncle. rande) Found in the Clinton limestone lenses in the Rome, Watertown and Ogdensburg railroad cut above Lewiston. Als
Size: 877px × 2851px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorne, bookcentury1800, bookdecade1880, booksubjectscience
