~oi YORKSHIRE TYPE AMMONITES— II Mar. 



1919 



Zoological Synopsis 



(Pis. I-CXXX. In presumed natural order — I-IV, simple to complex. Based 

 largely on the masterly works of Branco & Hyatt.) 



IV, Suborder, PHYLLOCAMPYLI, Hyatt 

 Saddles phylloid. 



3, Superfamily, Psiloceratacea 

 Phylloid saddles soon lost; hanging lobes oblique; IL. bifid. 



2, Superfam. Lytoceratacea, S. Buckman, pars* 



Phylloid SS., lost in highly specialized ; IL. cruciform. 



i, Superfam. Phylloceratacea 

 Phylloid SS. persistent; IL. bifid. 



III, Suborder, SCHISTOCAMPYLI 



Primitive ES divided (three-celled) ; sut-1. complex ; hanging LL. oblique. 



2, Superfam. Stepheoceratacea 



IL. pointed, 

 i, Superfam. Deroceratacea 



IL. bifid. 



II, Suborder, STENOCAMPYLI (= Leptocampyli, Hyatt, pars) 

 Primitive ES. narrow, deep ; oblique hanging LL. not developed ; IL. pointed. 



Superfam. Oppelacea 



I, Suborder, PLATYCAMPYLI (= Pachycampyli, Hyatt, pars) 

 Primitive ES. broad ; LL. ceratitoid in genera with simple sut.-l. ; IL. bifid. 



3, Superfam. Amalthacea 



(Cadicones) — serpenticones to oxycones, usually carinate. Sut.-l. often highly 

 specialized, L 1 elaborate. 



2, Superfam. Liparoceratacea 



Mainly capricorns to sphaerocones with complex sut.-l. No carina. 



i, Superfam. Ammonitacea 



Sut.-l. simple ; L l U-shaped, ceratitoid, elaboration (trilobulation) rare. Carina, 

 except in some primitives. 



Phylloid saddles indicate rapid early specialization ; but in conch- 

 contour IV lost ground in comparison with some competitors. In 

 II, I, oblique hanging lobes rare — only perhaps in a few oxycones with 

 much elaborated sut.-l. 



For classification of Families and Genera, see Zoological Analysis, 

 Appendix, p. b. 



* Jur. Amm. ; Geol. Mag. (4) I, (1894). 2 9 8 < 



