14 INFERIOR OOLITE AMMONITES. 



desirable and Hyatt's genera are being adopted in consequence of priority, it 

 becomes very bard to say to what to apply the genus Harpoceras. For instance, 

 in the genus Tropidoceras, Hyatt had placed Am. Actaeon and Am. Masseanus, 

 which "Waagen had specially mentioned, and Am. ojpalinus in the genus Lioceras. 

 We could then scarcely use Harpoceras as the generic name for some of the 

 remainder, because if we pursue the mode of division that we have sketched 

 out we should confine the genus within limits never intended by the author who 

 proposed it for " all Ammonites having a falciform sculpture and distinct keel," 

 and who showed by his list of synonyms 1 the wide application he intended for it. 



Haug, in his pamphlet on * Harpoceras,' makes three genera — Harpoceras, 

 Hammatoceras, and Hildoceras, for what Waagen intended as Harpoceras, and he 

 treats as subgenera of these Tropidoceras, Cycloceras, Sonninia, &c. Since we 

 intend to treat these latter as genera, this plan will not help us. We suppose, 

 however, that Harpoceras must not be rejected, but it is difficult to know how 

 best to apply it. 



Neumayr 2 has divided the subfamily " Ammonites " into four sections, viz. 

 Arcestidae, Tropiditae, Lytoceratidae, iEgoceratidae. The section iEgoceratidae he 

 divided into three subsections, viz. iEgoceratinae, containing iEgoceras and 

 Arietites ; Harpoceratinae, containing Harpoceras, Oppelia, Haploceras ; Stephano- 

 ceratinae, containing Stephanoceras, Cosmoceras, Ancyloceras, Perisphinctes, &c. 



Douville 3 has proposed to unite Arietites and Harpoceras into a tribe Harpo- 

 ceratinae; and Oppelia, Lissoceras(= Haploceras) and Neumayria into Lissoceratinae ; 

 and then these two, Lissoceratinae and Harpoceratinae, to " form a subfamily Harpo- 

 ceraticlae." I have given considerable time to the classification of these groups, 

 and I venture to suggest that the following method more nearly represents the 

 affinities of the various forms. It will be noticed that I have removed Amaltheus 

 from the Arcestidae, as I consider that its general shape, sutures, and structure 

 bring it into closer relationship with Harpoceras and Oppelia forms. 

 Family — Ammonitid/e, to contain subfamily Ammonites {i.e. what was previously 



included in the old genus), and also Hamites, Baculites, &c. 

 Subfamily — Ammonites, to contain tribes 4 Arcestidae, Tropiditae, Lytoceratidae, Mgo- 



ceratidae. 

 Tribe — Muoceratidm, to contain subtribes iEgoceratinae, 5 Harpoceratinae. 



1 Waagen, before quoted, p. 245 (67). 



2 ' Zeitschrift d. deutschen geol. Gesellschaft,' p. 854 — 942 (see p. 905), 1875. 



3 Zone of Am. Sowerbyi, 'Bulletin Soc. geol. France,' ser. 3, vol.13, P- 14. 



4 These divisions, as well as the one above (Ammonitidae), are called by Wright and Neumayr families, 

 but this seems confusing, since they are two different classes of divisions, and by Douville subfamilies. 

 This latter term seems in contradiction to the rule given by Strickland (' Scientific Writings, Zoological 

 Nomenclature,' p. 394) that families should end in idee and subfamilies in inoe. 



5 This includes Neumayr's Stephanoceratinse. See further on. 



