7909 HARPOCERAS 



SYSTEMATIC 



Generic Names 



Certain remarks on generic names will be assembled here, and will 

 be added to from time to time as may be required. It may be necessary 

 for the discussion of certain genera to notice others which are not 

 actually within the scope of this work. 



Genus, PLATYPLEUROCERAS, Hyatt 



1867, Foss. Ceph. ; Bull. Mus. Comp. Zool , V, 92. 



Hyatt quotes one species, P. lateecosta with three references ; but 

 it is evident from what he quotes that he has been misled by the wrong 

 numbering of Sowerby's PI. dlvi. Therefore, by latcBCOsta he means 

 brevispina ; and the other references which he quotes indicate this : 

 A. lateecosta, Zieten, A. natrix rotundus, Quenstedt, are both akin to 

 A. brevispina, Sowerby. 



It is advisable to take as type A. laftecosta, Zieten, non Sowerby. 



Result 



Genus, Platypleuroceras, Hyatt, 1867. Genolectotype, Am. 

 lateecosta, Zieten, non Sowerby. 



Genus, HARPOCERAS, Waagen, 1869 



i86g, Formr. Am. subradiatus ; Geogn.-I'al. Beitr. II, (2) 245 — 250. 



This genus was proposed by Waagen for a very comprehensive 

 series which the author himself admits had been already distributed 

 by Hyatt into several families and many genera. Waagen proposed 

 it specially for the Falciferi of the Lias (p. 250), as he shows by his name. 

 Evidently again from the nammg, out of the Falciferi, A. falcifer, 

 J. Sowerby, is the species rightly to be selected as the type. This 

 is the substance of what Dr. Haug wrote to me many years ago, in 

 I)roposing that the genus Harpoceras should be restrif ted to the true 

 Falciferi, with Am. falcifer as type (Geol. Mag., 1887, (3), IV, 400) ; 

 and this suggestion I carried out (Ibid., p. 397). 



The strong sickle-shaped ribs and the undercut umbilical edge are 

 special features of the genus. 



Result 

 Genus, Harpoceras, Waagen, Genolectotype, /I. /a/a/er, J. Sowerby. 



