. Bulletins of American paleontology. New Guinea Ammonites: Westermann & Getty 255 The costation consists of curved, dense, and sharp primaries which divide just below mid-flank into two, more rarely three very dense, prosoradiate and continuous secondaries. The outer whorls (>45-60 mm D) become gradually much more evolute, depressed and typically cadicone with vertical umbilical wall bounded by a weakly rounded margin marking the broadest whorl width. The primaries retract from the umbilical wall and become rapidly more widely spaced swelling into lower-lateral bullae while the sec- on
. Bulletins of American paleontology. New Guinea Ammonites: Westermann & Getty 255 The costation consists of curved, dense, and sharp primaries which divide just below mid-flank into two, more rarely three very dense, prosoradiate and continuous secondaries. The outer whorls (>45-60 mm D) become gradually much more evolute, depressed and typically cadicone with vertical umbilical wall bounded by a weakly rounded margin marking the broadest whorl width. The primaries retract from the umbilical wall and become rapidly more widely spaced swelling into lower-lateral bullae while the sec- ondaries remain dense, being about five times as abundant as the primaries. The full diameter is estimated at 100-120 mm. It ap- pears probable that the large body chamber fragments belonged to the same species as the smaller incomplete specimens. The juvenile septal sutme at a few millimeters diameter ( Leiden, st. 126194) has an oblique 'internal lateral lobe' separating the two saddles and a shallow (U^) lobe at the umbilical seam, in all closely resembling the early suture of B.} (Trepto- ceras ?), n. sp. A (Text-fig. 12). The 'internal lateral lobe' is, therefore, probably homologous with the primary 1st umbilical lobe, Ui. The mature external part of the suture (st. 126195) is mod- erately complex, consisting of subequal E/L and L/U saddles divid- ed by a narrow trifid L which is approximately as deep as E; U^ resembles L except for the somewhat smaller size; the other um- bilical elements are small and straight, the saddle line rising some- what toward the umbilical seam. Discussion. — The inner phragmocone whorls resemble certain Bullatimorphites Buckman, especially B. (?) sojamim (Boehm, 1912, pi. 35, figs. 2a-b) from the Bathonian-Callovian of the Sula Islands^) which also has dense, long, and curved primaries on the. Text-fig. 12. — Juvenile incomplete (internal) septal suture of Bullatimor- phites ? (Treptoceras) A $, at mm diameter, from Kemaboe V
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