History of British animals - University of Guam Marine Laboratory

238 MOLLUSCA. CEPHALOPODA. Okthocera.pers a little to the extremity, which is more obliquely placed than in theothers, and produced into a blunt knob at the upper margin. The apertureis likewise a little contracted.b. Extinct species.* Surface of the shell smooth.1. O. Icevis—Shell conical, partitions waved ; chambers large;syphonsmall and central. The length of the specimen which I possess is upwardsof 3 inches. The breadth at the base is T9 5 ths, and at the apex y^ths. Theshell isvery thin 2; chambers about T 5 ths of an inch in depth ; partitionswaved on both sides ; syphon in the middle of the shell about J 5 th of an inchwide.— O. superficie laevi, lire's Rutherglen, 30G, t. xvi. f. 3 O. Ivevis, Flem.Annals of Phil. v. 201, t. xxxi. f. 1.—In Carboniferous Limestone.2. O. pyramidalis —Shell tapering, partitions slightly waved ; chamberslarge, syphon small and central. This is longer in proportion to its breadththan the preceding ; the length of one specimen isupwards of indies ; 1 inch2 2and T 5 ths at the larger end, and T 5 ths at the apex the ; last formed chambersare nearly t 3 5 ths of an inch in depth, while the oldest, towards the point, are'scarcely T 3 th. A fragment found contiguous measured 2 inches in diameter.Flem. An. Phil. v. p. 202,t. xxxi. f. 2.—In Carboniferous Limestone.3. O. cylindracea— Nearly cylindrical, partitions slightly waved, chambersnumerous, pipe minute and central. In a specimen 3|th inches in length,T 4 5 ths at the base, and 3,th of an inch at the apex, the chambers are scarcelyl, 5 th in depth. When the shell is removed, the chambers appear very distinct,with a flat surface—Flem. An. Phil- v. p. 202, t. xxxi. f. 3 In CarboniferousLimestone and Slate-clay of the coal-field.4. O. convexa Nearly cylindrical, partitions thin and concave ; syphonlarge and lateral. In a specimen 4J inches long, the diameter at the basewas l£th, and at the 8apex ths., nThe lower chambers are about itfi of aninch in depth. The syphonis about 3 iths of an inch wide, and placed aboutmidway between the centre and margin—Flem. An. Phil. v. p. 202. t. xxxi.f.4. O. circularis, Sower. Min. Conch, t. 60. f. 0. 7- ?—In Carboniferous Limestone.5. O. attenuata.— Tapering, partitions nearly circular; chambers large.The shell of this species in one specimen is very thin, transparent, and glossy,and in some places is minutely striated across. Another specimen ^thslong, |th at the base, and j'gth at the apex, contains fifteen chambers InSlate-clay of the coal-field.G. O. Breynii — Conical, partitions waved on the syphon side the ; syphonitself is lateral, small, and cylindrical.— Martin, Pet. Derb. t. 39,f. 4. Sower.Min. Conch, t. 00. f. 5.— Carboniferous Limestone.7. O. undulata—Shell oval, thin, smooth ; partitions numerous, oblique,their edges rising, oval, with a wave on each side ; syphon lateral.—In CarboniferousLimestone.8. O. conica.— Shell long, conical, aperture oval ; chambers numerous ; sy-— phon small, oval, nearly touching the margin. Sower. Min. Conch, t. lx. f. 1,2, 3 In Lias. In the Geology of England and Wales, p. 208, this is consideredas the alveolus of a Belemnite.9. O. cordiformis.—" Obconical ; base contracted ; sides convex ; apertureround ;" septa numerous, placed directly across ; syphon not quite in thecentre, the tube of which is inflated into a globular form between each septum.—Sower. Min. Conch, t. ccxlvii—In Limestone of the Old Red Sandstone,Closeburn, Dumfriesshire.2