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IV.—Jurassic Ammonites: On the Genus Cymbites (Neumayr)1

Published online by Cambridge University Press:  01 May 2009

S. S. Buckman
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Extract

This paper deals with the species which are considered to belong to the genus Cymbites, and the reason for placing Paroniceras, Bonarelli, as a synonym. A few notes are added concerning Agassiceras, which is also affected; and a description of the little-known species Agassiceras Colesi (J. Buckm.) is given.

Type
Original Articles
Information
Geological Magazine , Volume 1 , Issue 8 , August 1894 , pp. 357 - 363
Copyright
Copyright © Cambridge University Press 1894

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Footnotes

1

See the author's previous paper, Geol. Mag. July, No. 361, p. 298.

References

page 358 note 1 Probably young forms of oxynotus.

page 358 note 2 These records may refer to Cymbites lævigatus (Sow.).

page 360 note 1 “Forms very doubtful as to their position”. —Unverm, Neumayr. Ceph. p. 67.Google Scholar

page 360 note 2 Fastigatus, rising evenly, like the roof of a house; sloping.

page 361 note 1 Through Polymorphites polymorphus (Quenstedt).

page 361 note 2 Through Microceras plamcostatum (Sowerby). The Stephanoceratidce are descended from the Deroceratiæ. The Amaltheidæ and Oppelidæ are not traceable to any of the Cymbites-forms directly, but they give ontogenetic evidence of a somewhat similar phase in phyletic development.

page 361 note 3 Smithson, . Contrib. Knowledge, 673.Google Scholar

page 361 note 4 To that series latum (“Coroniceras latum” Hyatt) should probably be added as the form connecting Agassiceras with Coroniceras. The readiest generic distinction between Coroniceras and Agassiceras will be found in the greater degeneration of the septa in the latter, Coroniceras proper being distinguished by long lobes.

page 362 note 1 Included by authors under the name Scipionianus, evolute and involute forms may be distinguished—the former in Reynès and Wright's figures, the latter in d'Orbigny's. Certainly Reynès calls his “Ammonites Scipionis”, but this is only short for Scipionianus, d'Orbigny, whose authority he gives. Hyatt, however, distinguishes Agassiceras Scipionianum and Ag. Scipionis as two species. His “Ag. Scipionis” seems to be divisible into three: 1st, Scipionis (Reynès), which he quotes—an evolute form of Scipionianus, as alluded to above; 2nd, Scipionianum olifex (Quenstedt, Amm. Schwab. Jura, pl. 17, tigs. 7–10), which he also gives in his synonomy—this seems to be a costate retrogression of Scipionianum, and therefore a cousin of Colesi, from which it differs in being more involute, more closely eostate to a larger size, and it probably deserves distinction as Agassiceras olifex; 3rd, a form of which an outline sketch is given in pl. 13, fig. 8 (Genesis Arietiæ)— a much more involute fossil than olifex, apparently very retrogressive, deserving a distinct name.