OCR Text |
Show 371 cost ® , one or two more very obscure ones are seen, which do not reach either the peripheral or umbilical margin. • The septa are strongly undulating, and irregularly divided into very unequal principal and subordinate lobes and sinuses on each side. Siphonal lobe comparatively small, and provided with three short branches on each > side, the two terminal of which are a little larger than others, slightly spreading, and merely a little dentate on their margins; first lateral sinus . about twice as large as the siphonal lobe, and very unequally divided into three branches, the outer one of which is largest, and truncated at the end, with four short, nearly simple, subdivisions, while the middle branch is smallest, with merely deeply sinuous margins, and the third one is tripartite and directed nearly inward toward the umbilical side; first lateral lobe small, slender, veryoblique, bipartite, with unequal bifid terminal branches; second lateral sinus scarcely larger than the oblique branch on the inner side of the first, very oblique, with an extremely contracted body, and two or three alternately- arranged, short, sinuous branches on each side; second lateral lobe longer than the first, somewhat arcuate, with a slender body, a trifid extremity, and three or four short, alternately- arranged, slightly dentate, lateral branches; third lateral sinus smaller than the second, with a proportionally less contracted body, and about three short, alternating, unequal, nearly simple, lateral branches, and a small, simple, subglobose, terminal division; third lateral lobe projecting* little beyond the second, and almost exactly like the first, excepting that its corresponding branches are on the opposite sides: fourth lateral sinus extremely broad, or more than equaling the breadtn of the first, which it also nearly equals in length, slightly divided at the end into two nearly % equal, short, broad divisions, with more or less sinuous margins: fourth lateral lobe nearly as large as the third, but owing to the undulating arrangement of the whole series, much less prominent, divided at the end into two short, equal, bifid branches, with obscurely dentate margins ; fifth, sixth, and seventh lateral lobes of nearly equal size, and scarcely half as long and wide as the fourth, with merely dentate extremities and lateral margins- all separated from each other by lateral sinuses of about the same size. I was at one time of the opinion that the three divisions of the septa. here described as the first, second, and third lateral lobes formed, together with the great undulation of the suture with which they connect, one enormously- developed first lateral lobe, which would also make the very broad sinus I now view as the fourth, the second lateral sinus. It now seems to me, however, from analogy, on comparison with the sutures of Placenticeras placenta (= Ammonites placenta, DeKay), that the view taken in the above description of the septa is the proper one. The specimen from which the figure and description of this species were made out consists of about one- half of one volution, most of which is non - septate. When entire, the shell must have measured not less than 4 inches in its greatest diameter, and about 1.13 inches in convexity. Locality and position.- Komooks, Vancouver's Island; Cretaceous. Genus PHYLLOCERAS, Suess. PHYLLOCEEAS ? RAMOSUS, Meek. Plate 5, figs. 1,1 a, and 1 b. Ammonites ( Scaphites?) ramo$ u$, Meek ( 1857), Trans. Albany Institute, vol. \ v, 45.- Gabb, ( 1864) Geological Report of California, vol. i, 65, pi. 11, figs. 12 and 12 a; and pi. 12, fig. 12 6. Shell oval- discoid in form, compressed, very thin and fragile; narrowly rounded on the periphery; umbilicus very small, but not entirely closed |