RfiSUMfi. 127 



This family contains, according to Zittel, three genera, Harpoceras, Hammato- 

 ceras, Oppelia; and these are again subdivided into groups around certain typical 

 Ammonites. With the first only of these genera are we concerned at present. 

 This one, Harpoceras, is divided into two parts (p. 459) : 



I. Formenreihen mit Arieten-Gepr'&ge. 



This included five groups, a — e. 



a. Gruppe des Am. algovianus. 



b. Gruppe des H. bi/rons (Hildoceras, Hyatt; Lillia, Bayle). 



c. Gruppe des Am. hecticus. 



d. Gruppe des Am. canaliculatus. 



e. Gruppe des Am. trimarginatus. 



II. Formenreihen der typischen Falciferen. 



This contains three groups. 



a. Gruppe des Am. radians (Grammoceras, Hyatt). 



b. Gruppe des Am. complanatus (Lioceras, Hyatt). 



c. Gruppe des Am. aalensis {Ludioigia, Bayle), containing Am. aalensis, Ziet., 

 Am. costula, Reinecke, Am. opalinus, Reinecke, Am. Murchisonce, Sowerby. 



Before discussing this scheme, I will give the manner in which Haug 1 arranged 

 these and similar Ammonites, namely, as follows : 



I. Haepoceratid^i. 



Gekielte Nachkommen der Aegoceratidse. 



a. Harpoceras, Waag. em. Haug. 



a. — a. Untergattung Gycloceras, Hyatt em. Haug. 



a 2 . ,, Dumortieria, Haug. 



(3. ,, Tropidoceras, Hyatt em. Haug. 



y. ,, Grammoceras, Hyatt. 



S. Harpoceras s. str. Haug= Leioceras, Hyatt, p.p. 



5 1 . Gruppe des Harpoceras kurrianum. 



5 2 . ,, ,, falciferum. 



5 3 . ,, „ lythense. 

 <5*. ,, „ opalinum. 



e. Untergattung Lioceras, Haytt em. Haug. 



1 "Beitrage Monog. Harpoceras," ' JVeues Jahrbuch fur Mineralogie,' Beil.-Bd. ii, 1885. 



