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Show 367 known, however, it differs in the details of its septa, while in the peculiar flattening of its dorsal or antisiphonal side it differs not only from the last but from any other species of the genus known to me. I noticed this peculiarity in the specimen first referred provisionally to Say's B. * ovatus, but supposed it due to some accident. The collections subsequently obtained, however, show that it is not due to accidental pressure. It must be remembered, however, that individuals of the same species in this genus are subject to some variations of form as well as of the details of the septa; while they often present so few characters upon which to found species that their proper classification is generally very difficult, excepting to those who would refer all such forms throughout the world to the single species B. anceps of Europe. This form bears somewhat the same relations to the last that B. compressus, Say, bears to his B. ovatus, its septa being very like those of the former; so far as known, however, it seems never to be so compressed as B. oom-pressus at any stage of growth.* Locality and position.- Same as last. Genus HETEROCERAS, d'Orbigny. HETEEOCEBAS GOOPEBI, Gabb ( sp). Plat © 3, figs. 7and7a. Ammonite* t Coqperi, Gabb ( 1864), California Geol. Report, i, 69, pi. 14, figs. 23 and 23 a. Of this fossil, there is in the collection bnt a single non- septate frag * , ment, measnring3.50 inches in length and about 1.90 inches in its greatest breadth; the section being slightly oval. It is evidently a part of a spiral shell, with rounded disconnected whorls; and, judging from its curve, it must have possessed a much larger umbilical space than is seen in Turrelites. As it is very much larger than any known HeUcoceras, it would seem to have belonged to the non- septate part of a shell allied to Heteroceras. Its surface is ornamented by moderately distinct annular cost ® , which pass around rather obliquely. Two rows of nodes also occur on the outer or dorsal side, at which points the cost ® usually bifurcate. I refer this shell with much doubt to the species described by Mr. Gabb under the name Ammonites f Cooperi, which it seems probable was founded on a fragment of a Heteroceras. Mr. Gabb referred his species doubtfully to the genus Ammonites, as he had only mere fragments for study. Locality and position.- Komooks, Vancouver's Island; Cretaceous. Genus AMMONITES, Brnguifere. f AMMONITES NRWBERRYANTTS, Meek. Plate 4, figs. 3, 3 a, and 3 ft. Ammonites Newberryanus, Meek ( 1857), Trans. Albany Institute, iv, 47 ( not A. Xew-berryanue, Gabb. ( 1864), Geol. Report California, i, 61, pi. 27). Shell discoid, moderately compressed, rounded on the periphery; umbilicus of moderate depth, less than one- third the greater diameter • Since this was written I have ascertained that large specimens of B. compreseus show a tendency to present a similar subtrigonal section ( see Invert. Pal& ont. Upper Mo., 403), from which it would appear that this Vanconver form may be more nearly related to B. compreseus than has been suspected. tNone of the species here described belong properly to the genus Ammonites, as restricted by late inyeetigators of the family Ammonitid*. As the Cretaceous groups of |