OCR Text |
Show 365 deep and nearer the antisiphonal side: siphonal projection of lip rather long and linguiform, while that of the dorsal side is nearly semicircular in outline. Surface entirely smooth, or with only obscure lines of growth, curving parallel to the projections and sinuses of the lip. , Septa moderately approximate but not crowded; lobes and sinuses on opposite sides of the shell sometimes differing slightly in their details. Siphonal lobe shorter than the first lateral, and a little more tfcan one-third wider, provided with two rather large, widely- separated terminal branehee, with each about six or seven small, short, unequal subdivisions, some of the larger of which are bifid and others trifld. First lateral sinus of about the size of the first lateral lobe, and divided at the extremity into two short, aubequal, trifld, terminal branches, with sinuous and obtusely digitate margins. First lateral lobe * little longer than, and about as wide ap, the $ rst lateral sinus; on one side of the qjiell sometimes ornamented by five short, nearly equal, palmately-spreading branebes, with from four to five dictations each ( see fig. 2 0), while on the other it is sometimes divided at the extremity iato four unequal branches ( see fig. 2 6, plate 4), one of which is considerably longer than the others, and more or less distinctly bifid and digitate* Second lateral sinus of nearly the same size and form as the first. Second lateral lobe a little shorter than the siphonal lobe, and about two- thirds as wide, nearly equally divided at the extremity into two short, spreading branches, of which the one on the siphonal side is provided with four short, unequal, digitate subdivisions, and the other into two very unequal branchlets, the larger of which has four or five digi-tations. Antisiphonal lobe about half as long as the adjacent side of the second lateral lobe, near half as wide as long, and ornamented by four or five digitations on each side. * The largest fragment in the collection measures 1.49 inches in its greater diameter, and 1.13 inches in its smaller, and, judging from its very gradual taper, it appears to have been, when entire, as much as 12 or 15 inches in length. At the time I proposed the name B. inomatus for this species, I only knew Dr. Trask's B. Chkoensis from his figures and description of a very small specimen, giving scarcely any idea of the septa of what is now known to be a very young individual of his species. Since seeing Mr. Gabb's figures of the larger specimens of the same shell from the original locality, I am led to think that our Sucia Island specimens may belong to the same species. Of this, however, I cannot be positively sure without a better series of specimens for comparison, particularly as our specimens differ somewhat in the details of their septa from Mr. Gabb's figures, and are still considerably larger than those illustrated by him. In its septa, it agrees more or less nearly with £. grandis, H. and M., and B. ovatu*, Say, but it seems sever to attain 9 si* e approaching that of the adult shell of either of these forms, while it is destitute of the lateral undulations of the same, so far as can be determined from our specimens, though Mr. Gabb figures one individual that he refer* to Dr. Trask's species with these undulations well developed. It is worthy of note, however, that his specimen showing this character differs materially in other respects from our specimens, as well as from the other referred by him to the B. Chicoensis. Locality and position.- Cretaceous of Sucia Islands. |