. Mesozoic fossils. , California, where it appears to betolerably abundant. Uiitil Mr. Eichardson collected the specimens de-scribed above from the Islands in Skidegate Channel, the sjiecies had notbeen obtained from any other locality. Ammonites difficilis of DOibigny, a French Neocomian fossil, is itsnearest Eui-opean representative. B(jth A. difficilis and A. Brewerii arevery abnormal representatives of the Cl3peiformes, but as DOrbigny and M Pictet place A. in this section, A. Brewerii is included in it latter pahuontologist saj^s that A. dijficilis makes a transition
. Mesozoic fossils. , California, where it appears to betolerably abundant. Uiitil Mr. Eichardson collected the specimens de-scribed above from the Islands in Skidegate Channel, the sjiecies had notbeen obtained from any other locality. Ammonites difficilis of DOibigny, a French Neocomian fossil, is itsnearest Eui-opean representative. B(jth A. difficilis and A. Brewerii arevery abnormal representatives of the Cl3peiformes, but as DOrbigny and M Pictet place A. in this section, A. Brewerii is included in it latter pahuontologist saj^s that A. dijficilis makes a transition to the Ligati. Group II.—Mammillatl, Pictet. Ammonites Stoliczkanus, Gabb.—Variety spiniferus. Plate III., fig. 3, and Plate IV., fig. 1. A. , Gabb. Palaiontology of California. Vol. II., page 135. Plate XXIIL, figs. 16, Ida. fedScir:)? , ;fii. Fig. 2. Fig. 2.—Ammonites Stoliczkanus, Gabb., var. spiniferus. Fragment showing thespinous nature of the tubercles. Shell thick; whorls wider than high, compressed on the siphonaledge and inner half of the sides; umbilicus not very large, but deep;surface heavily costate; ribs tuberculate, except on the centre of thejjeriphery. Whorls live, increasing rather rapidl} in size, about one-half of theinner ones being ex])osed. The volutions are always broader than high;in a well-preserved specimen an inch in diameter, they are distinctly 25 though obtusely bicarinatc on tlie periphery, and oljsoletel} keeled atthe sides. With the increase of g-rowth the keels diisappear, and thewhorls become more rounded, until tinally the last one assumes a sub-quadrangular aspect. The inner half of the sides of the body whorl iscompressed, the outer half curves convexly and rather obliquely towardsthe periphery, which is broad and flattened. The umbilical face of thisvolution is squarely as well as ve
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Keywords: ., bookcentur, bookdecade1870, booksubjectpaleontology, bookyear1876
