1923 SYSTEMATIC 57 



These references axe the same as the first four given by Bruguiere, so 

 the selection is narrowed dowTi to them. As it happens, the\' only 

 represent two specimens ; for the two figures of Lister are the same, 

 while the figure of Bourget is a reversed copy of that of Lang (Langius). 

 Selection as between these two specimens is settled by Fischer (Man. 

 Conch. (Fasc. 4), 1882, p. 390), somewhat indirectly. He definitely 

 selected Amtnonites hisitlcatus, Bruguiere, and showed that he fixed on 

 an Arietes by giving a figure of such a form as Am. hisitlcatus (PI. Ill, 

 fig. 7). But this figure cannot be the t^-pe, as it is later than Bruguiere. 

 However, as it is an Arietes, it excludes the figure of Lister, which 

 represents one of the Amalthei. 



Lister's figure now reproduced, PI. CCCXCII, is the holot\*pe of 

 Ammonites bisulcata, Bruguiere, for that author gives to it the definite 

 commendation " Icon, bona." Such special selection of a figure marks 

 it off from its feUows and elevates it to chief place — holotype. The 

 figures of the other authors cited by Bruguiere, therefore, are paratypes 

 of Am. bisulcata. The figures of Lister, Lang and Bourget are the 

 genolectot\T)es of the genus Ammonites according to Lamarck's choice, 

 which is further narrowed, by Fischer's exclusion of Lister's figure, 

 to the parat\T)e of A. bisulcata figured by Lang. Therefore, a paratype 

 of A. bisulcata becomes the genolectotviJe of Am)nonites, but cannot 

 retain the trivial name bisulcata, because that goes to the holotype. 

 This holotype being a Paltopleuroceras, takes the specific title Palto- 

 pleuroceras bisulccUum, Bruguiere sp. (see PI. CCCXCII), while the 

 paratype retains the generic name Ammonites. As it seems to be 

 identical ^vith A. bucklandi, Sowerby, it takes that trivial name, and so 

 has the specific title Amtnonites bucklandi, J. Sowerby (see PI. C XXXI a). 

 'Planulites, Lamarck, 1801. This author (op. cit. pp. 100, loi) 

 separated from Ammonites two genera : Orbulites, which may be a 

 Goniatite, and Planulites, which has been supposed to be a Clymenia. 

 But as Lamarck definitely gave the name Planulites sulcata to the 

 example figured by Bourget (Petrif. xlvi, 290), that becomes the 

 genotype, though Lamarck's description might fit Clymenia. Bourget 's 

 figure, here reproduced for reference (PI. CCCXCIII), would appear to 

 be a Hildoceratid. The shading indicates, presumably, quite a shallow 

 lateral sulcus — a character recalling Hildoceras and some Hildoceratoid 

 forms which may be new. 



The follo\nng alterations of generic names are required : — 

 Alligaticeras, nov. Genotype Am. alligatus, T.A. CCXII. Differences 

 from Dichtomoceras :— external, ribs versi-radiate and presence of 

 parabolae : internal, ES with only small accessory lobe ; L2 < Aux. i 

 instead of L2 > Aux. i. 



For Dichotomoceras as generic name of Am. ingens (PL CLXXXH"), 

 it is advisable to substitute temporarily " Perisphincies." For Dicho- 

 tomoceras as hemeral term for hemera post- martelli, antecedens may be 

 substituted. The hemera dichotomum is much later, see pp. 35, 39, 40. 



Ac KXOWLE DGME N T 



The Author's hearty thanks are offered to all those who have aided 

 in this work : their names are already recorded in pre\'ious volumes 

 or are noted in the legends of the plates. To them must, however, 

 be added for special thanks. Professor Edgar Dacque, Munich Museum, 



