OCR Text |
Show 366 BACULITES OCCIDENTALIS, Meek. Plate 4, figs. 1,1 a, b. Baculites ovatus ( Say?), Meek ( 1857), Trans. Albany Inst, iv, 48. BaculiUt occidental*!, Meek ( 1861), Proceed. Acad. Nat. Sci. Philad., xiii, 316. Shell attaining a medium size, very gradually tapering; section sab-trigonal, excepting near the smaller end, where it is more nearly ovate; antisiphonal or broader surface flattened so as to give its lateral margins a more or less angular appearance; sides converging with slightly convex outlines from these angles to the narrowly rounded or obtusely angular eiphonal margin; aperture subtrigonal, with the antisiphonal margin of the lip nearly semicircular, and that of the si phonal side much longer and somewhat cnneate- snblinguiform, while the lateral sinuosities are rounded with a long, nearly straight, oblique margin on the siphonal side. Surface ornamented with small, obscure, regular undulations, extending across from the dorso- lateral angles to or beyond the middle of each side; with a regular curve parallel with the margins of the lateral sinuosities of the lip. Fine rather regular but obscure lines of growth also run parallel to the curves of the lip margin.* Septa neither crowded nor very distant. Siphonal lobe somewhat shorter than the first lateral lobe, and twice as wide, provided with two rather large, widely- separated terminal branches, each of which is bifid, the subdivisions being armed with numerous unequal, rather sharp dig-itations. First lateral sinus of about the breadth of the siphonal lobe, near one- third longer than wide, and deeply divided at the extremity jnto two nearly equal branches, each of which is tripartite, with short obtuse sinuosities and digitations. First lateral lobe as long as the second, but only about two- thirds as wide, and provided with three principal branches on each side, the two terminal of which are a little larger than the succeeding lateral divisions, and each armed with from six to eight or nine small unequal branchlets and digitations. Second lateral sinus a little broader than the first, but in other respects very similar to it, excepting in having its corresponding branches on opposite sides. Second lateral lobe nearly as wide as long, its antisiphonal side being only about half as long as the other, awing to the shortness of the antisiphonal sinus, provided at the extremity with four pal-mately- spreading branches, the two inner of which are larger than the others, rather widely separated, and each irregularly trifid and more or less digitate. Antisiphonal lobe about half as long as the longer side ef the second lateral lobe on each side, lance- ovate in form, and provided with some five or six digitations on each lateral margin, one of which near the middle of each side is considerably longer than the others. The specimens yet known being all imperfect, it is not possible to give accurate measurements from them; though, as nearly as can be determined from the taper of the longest fragments in the collection, the average length of a specimen measuring 1.45 inches in its greater diameter at the larger end would appear to have attained a length of 12 to 15 inches. Although I continue to regard this form as being specifically distinct from the last, I am prepared to believe that more extensive collections may yet show it to be only a variety of that species. So far as yet * On each Bide of the specimen represented by fig. 1 of plate 4, there is a curious backward flexure of the lines of growth along an imaginary line near each dorso- lateral angle as seen at ( a) of the figure mentioned. As this character, however, is only seen on this one specimen, it is doubtless due to some accident. |