396 8. 8. Buchnmi- — On Jurassic Ammonites. 



To conclude, from the preceding remarks, I think that Bernis- 

 sartia cannot be considered as a synonym of Sylceochampsa, and, 

 that consequently, the name of the Crocodilian of Bernissart ought to 

 be retained, instead of placing it in a list of synonyms. 



Ill- — On Ammonites serpentinus. Eeinecke, Am. falcifer, Sowb., 



Am. elegans, Sowb., Am. elegans, Young, etc. 



By S. S. EucKMAN, F.G.S. 



I HAVE had occasion lately to thoroughly investigate these and 

 other allied Ammonites, partly because it has been important 

 to me that I should know the true affinities of these species, partly 

 because my attention was directed to certain still obscure points 

 with regard to their identification, and partly on account of the 

 statement by the late Dr. Wright that Am. serpentinus and Am. 

 falcifer were the same species. In pursuing my investigations I 

 have received a great deal of assistance from Dr. E. Hang's Beitrage 

 zu einer Monographic der Ammoniten-gattung Harpoceras,^ which 

 I am pleased to acknowledge, although I do not find myself able to 

 agree with him in one or two small points which I will presently 

 mention. Meanwhile, by the aid of a few references to well-known 

 works, I will indicate the Ammonites so that they may be understood. 



HiLDOOERAs ? SERPENTiNUM (Ecinecke). 



1818. Argonauta serpentimis, Eeinecke, Maris protog., p. 89, iig. 74-75. 

 ? 1822. Ammonites Strangewaysi, Sowerby, Min. Conch, t. 254, tig. 1 and 3. 

 Non Am. serpentimis, D'Orb. (figure reduced), Wriglit, Bayle, etc. 



This Ammonite seems to be extremely scarce. "What has been 

 called by D'Orbigny, Wright, and others, Am. serpentimis, and is so 

 labelled in museums and private collections, is the Ammonites falcifer 

 of Sowerby, which has been erroneously supposed to be the young 

 state of Am. serpentinus (Eeinecke). Oi^pel, in his Juraformation, 

 p. 243, noticed that this was not so, and keeps both species distinct ; 

 and Dr. E. Haug, in his Beitrage Monog. draws pointed attention 

 to the fact of falcifer having been generally figured for serpentinus. 

 Dr. Haug corrects this error, and separates the -4m. serpentinus totally 

 from Am. falcifer, placing Am. serpentinus in the group of Am. hifrons, 

 and consequently in Hyatt's genus Hildoceras. The form of the 

 inner margin, the general outline of the ribs, obscure, it would 

 seem, on the inner part of the whorl, seem to warrant this ; but at 

 the same time it lacks the furrows on each side of the keel present 

 in Eild. hifrons. Of its suture-line I can say nothing, but the suture- 

 line of Eild. hifrons is very distinctive. To whatever genus the 

 true Am. serpentinus belongs, I feel convinced it does not belong to 

 the same genus as Am. falcifer; and that Am. falcifer does not belong 

 to the genus Hildoceras is very clear, on account of the suture-line, 

 the shape of the inner margin, etc., but especially on a distinctive 

 structural difference in the keel. The keel of Hildoceras hifrons is 

 filled by the mould, and is the same shape in reference to the ventral 



^ Nenes Jahrbuch fiir Mineral. Beil. Bd. iii. 1885. 



