iv YORKSHIRE TYPE AMMONITES-II May 



Genus, GEYERINA, nov. 



Type, Geyeria fasciata, S. Buckman 



A necessary change of name : Geyeria was forestalled by a few 

 months The W is in Mon. 1.0. Amm., 1899, Suppl., PI. VI, figs. 

 17-19. 



Genus, EUHOPLOCERAS, nov. 



Type, Sonninia acanthodes, S. Buckman 



The name was chosen many years ago for the purpose of describing 

 the concavum [and discites] zone Sonninines. They were, however, 

 ranged under Sonninia, in deference to the prejudice about too many 

 generic names. It was a mistake. The massive quadrate-whorled 

 Sonninines with broad, flattened periphery and low keel are quite distinct 

 from the true Sonninice with much compressed, broad whorls, narrow 

 periphery and high keel. 



The type is in Mon. I. O. Amm. PI. lx. All the species described 

 in that work as Sonninia in Pis. xlviii-ciii should be placed here. They 

 belong to several series, which pass independently through catagenetic 

 phases from spinous to smooth. 



Derivation : — lv well, on\a, weapons. 



Genus, PLANITES, de Haan 



1825, Amm. et Goniat. pp. 34, 79-94. 



Testa septata, septis frondosis, discoidea, spiralis : anfractibus vix 

 involutis, sensim incrassatis " (p. 34). Species analysed and described, 

 pp. 79-94. 



No type was selected, but according to the name Planites planulalus ; 

 de Haan sp. appears to be the natural type. It was founded on " Am. 

 planulatus, Schlotheim, 1 a," and Am. brodicei, Sowerby. The former 

 (ia) stands for " Am. polygyratus Reineckii," — Schlotheim, Petref. 1820, 

 pp. 59, 60. 



Planites then would become the generic name for Siemiradzki' s 

 " Mutationsreihe des Per. polygyratus " (1898, p. 161). 



Planites is a generic name which has been overlooked, being a 

 premature attempt at the generic division of Ammonites. It was intended 

 for those species which are feebly involute serpenticones. Most of the 

 species allocated to it by de Haan have modern generic names, but 

 A. planulatus, Schlotheim, may be regarded as a division of Biplices 

 (Perisphinctes) which is sufficiently free. 



Result 



Genus, Planites, de Haan, 1825. Genolectotype, P. planulatus, 

 de Haan, pars, = A. planulatus, Schlotheim, ia, = Nautilus polygyratus, 

 Reinecke = Perisphinctes polygyratus, as interpreted by Siemiradzki, 

 1898, p. 167. 



