[NVEETEBRATE PALEONTOLOGY. 445 



AMMONITID^E.* 



Genus AMMONITES, Brug. 



Synon.—Cornu Ammonis, Ammonites, Hammonites, Harmonites, &c, wholly or in part of pre-Linmean 

 authors. 



Ammonites, Bruguieie (1789), Eucyc. Moth. 1, xvi, ami 28.— Lamarck (1799), 79; and (18C1) 

 Syst. An., 100.— Blaiuv. (1824), Diet. Sci. Nat., XXX, 185.— D'Orbigay (1826), Tal>. 

 Meth. ; and (1841) Pale"ont. Pr., Terr. Cr6t., 1. 369; also (1842) ib.. Terr. Jnraas., I, 

 185.— Deshayes (1830). Encyc. M6th., II. 226.— Roemor (1836), Verst. Nordd. Ool., 180.— 

 Owen (1838), Trans. Geol. Soc, II. part 2d.— Geinitz (1846), Grundr. d. Verst., 28:>; 

 and of numerous later authors. 



Argonautites, Montfort (1802), Hist. Moll., Ill, 394. 



Pelagusi, Planulites, Simplegades, &c., Moutfort (1808), Conch. Syst., I. 



dmmonita, Gray (1821), London Medical Repository. — Fleming (18-28), Brit. An.. 240. 



Coronoceras, H\att (1868), Bull. Mus. Corap. Zool. (5), 77. 

 # 



Elgin. — Amnion, a name of Jupiter. 



Type. — Ammonites bisulcatits, Brug. 



Shell discoid, or more or less convex, with periphery rounded, flattened, 

 concave, cuneate, or keeled with or without furrows; keel, when present, 

 simple or crenate ; volutions all regularly coiled on ihe same plane, and 

 contiguous, or to a greater or less degree embracing; umbilicus varying 

 greatly in breadth and depth with the species; surface smooth, striated, or 

 costated, and often nodose, or rarely subspiniferous ; aperture differing 

 ir.'.ch in form; lip simple, thickened, hooded, or with variously-formed 

 lateral appendages; septa with lobes and sinuses varying in number, and 

 more or less branched and digitate. 



The foregoing synonymy and diagnosis are intended to conform to the 

 old comprehensive views in regard to the limits of the genus Ammonites', 

 not by any means, however, because I believe that, as thus defined, it repre- 

 sents a homogeneous group, but because I have to dispose of a species here, 

 which, from such specimens as are available for study, it is only possible to 

 refer, in a general way, to that group as formerly understood. 



The old genus Ammonites has of late years been carefully studied by 

 Professor Hyatt of this country, and Professor Suess, Dr. Zittel, Dr. Laube, 

 and others of Europe, and divided into numerous distinct genera; but as 

 their labors have been mainly confined to Jurassic and Triassic types, it is 

 not probable that any of the shells here described would property fall into 

 their newly-established genera. With one exception, 1 have not cited any 

 of their new names in the synonymy of this genus here, because I really do 



* I am under obligations to Prof. Alpheus Hyatt of the Bostou Society of Natural History, who 

 has devoted much attention to the study of the Ammonitoid types, for suggestions in regard to some of 

 the forms I have here ranged under the family Ammonitidai. 



