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Show 368 of the shell; volutions Ave and a half or more, increasing very gradually in size, diameter from ventral to dorsal side nearly or quite equaling their transverse breadth- all rather deeply embracing, so aa to conceal more than half of each inner tarn. Surface ornamented by distinct rounded cost ® , which occasionally bifurcate near the umbilicus and about half- way across toward the periphery, in crossing which they curve slightly forward; depressions between the eostm generally abomt equaling the latter in size, but, at intervals of about Jive or six times fee each turn, a deep sulcus or constrictive is seen on internal easts, produced by the oocaskmal thickening of the lip, at regular intervals of about every fifth of each turn. A single row of small tranaversely-elongated nodes surrounds the umbilicus. Septa deeplv divided into six or seven principal lobes on each side, which diminish regularly in size from the first. lateral lobe to the umbilicus. Siphonal lobe about the size of the first lateral sinus, oblong in form, and provided with three principal branches on each side, the two terminal of which are larger than the others, and each irregularly subdivided into two or three small branchlets and a few sharp dictations. First lateral sinus deeply divided at the extremity into two sub-equal parts, and provided on each side behind these with two or three irregular alternating lateral branches- the two terminal divisions being much larger than the others, and each irregularly tripartite, with sinuous and digitate margins. First lateral lobe about the size of the first lateral sinus, palmately divided at the- extremity into three large irregular branches, with each three or four sharp unequal digitations at the end; while above these terminal divisions, the sides of the lobe are each ornamented by two or three smaller alternating sinuate lateral branches. Second lateral sinus smaller than the first lateral lobe, and having on each side two or three irregular alternating lateral divisions, while the extremity is divided into two unequal terminal branches, each of which is again divided into two or three small branehlets, with sinuous margins. Second and third lateral lobes much smaller than the first lateral, but somewhat similarly branched, their divisions being, however, proportionally shorter. The three or four remaining lobes are very small, a little oblique, and merely digitate. The specimen from which the foregoing description was made out measures 2.28 inches in its greatest diameter and 0.90 inch in convexity. As it consists entirely of septate whorls, it is probable that the outer volutions of adult individuals may vary somewhat in their external ornaments, as well as in the details of their septa, from the specimen under examination. In form and other external characters, this species is nearer like A. mutabilis of Sowerby ( Min. Couch., iv, 145, pi. 405) than any other shell with which I am acquainted. 1 have not had an opportunity to see the septa of that species; but if it is, as some think, not distinct from A. Koenigii, Sowerby, our Vancouver species may be readily distinguished by its more deeply- lobed septa. Named in honor of Prof. John S. Newberry, State geologist of Ohio, and professor of geology in the School of Mines, Columbia College, New York. Locality and position.- Same as last. these Cephalopoda have not yet been classified, however, in accordance with the prevalent modern views, and I have not the necessary material at band to determine the exact relations of onr species to some of the proposed genera, I have conclnded to leave part of them, for the present, nnder the old genus Ammonites, as understood in its moss comprehensive sense. |
