fi>()i;a of ruK suasta fukmation. 245 



1S70. Dioonites Buch'uinus (Ett.) Born. Scliiinpcr: Pal. Voj;., Vol. II, p. 140. 



1589. Dhxinitcs Bitcliianus (Ktt.) Bmii. l-'oiitainc: rotoiuiic Flora (Moiio^r. I'. S. 



(!(■<)!. Surv., Vol. Wt. p. Isj, j)l. Iwiii, i\'^. I; pi. Lxix, lio;^. 1, :!; pi. l.x.x, 

 fi<^8. 2, '.i; pi. Ix.xi. lii,'. 1 : pi. l.x.xii. Iii;s. 1. la. '_', Ja : pi. l.xxiii. lii;H. l-;5, .'ia, Ml); 

 pi. l.xxiv. 



1590. Zamiophiillntn Buchlanum (Ktt.) Xalli.: Dcnkschr. AVicii Akad., Vol. lA'll, 



|). 1(1 [()], pi. ii, ii^'s. I, '_'; |)l. iii; |)l. \, lio;. i.>. 

 18!).5. Zaiiiilis Jhtrliidiiiis (Ktt.) Scu. : W'caidcii Flora, I'l. II, p. 7!>, |)l. iii. liijs. 1-5; 

 ])l. iv: pi. viii. H<j;. 1 . 



^pcH'iinen.s of probable Diuoni/cs Jhichidnus, of ratlier (loiibtful 

 c'hai'actor, occur at localities Nos. 1, 15, 20, and 22. They are doubtful 

 l)(>cause they are composed of fi'aiiinent.s of detaciied leaflets. But at 

 locahty No. 17, in tlie lower pai1 of the Horsetown beds, Messrs. Ward 

 and StoiTS found seven specimens of this plant which admit of no doubt. 

 They show portions of the midrib with leaflets attached. These have 

 all tlie characteristic features of Diooniles Buchiaims. Many of these 

 features are so well marked and characteristic of this plant that there is 

 no occasion for confounding it with any other, provided they are dis- 

 tinctly displayed. This makes the plant especially \alual)le in tlie 

 (HMiiparison of the geological age of strata. It is to be noted that it 

 occurs here in the Horsetown l;)eds, whose age has been determined 

 from the marine invertebrates which they contain to be Lower Cretaceous. 



Figs. 16 and 17 give representations of two of these specimens. 



Dioonites Buchimms seems to have harl a world-wide distribution, 

 and it has always been found only in Lower Cretaceous strata. It was 

 first found in the Urgonian beds of Grodischt. Later the writer discov- 



hauson's plant to Dioonites with doubt and in an ul).scuro manner, but Schimper (Pal. Veg., Vol. II, p. 149) 

 (lid the same thing independently, and evidently without any knowledge that Borneniann had already done so. 

 Mr. Seward includes in this species the Cenoinanian Pleropht/Hiiiit aaxuniciiin Reich , so named hv Reich in the 

 Freiberg Mu.seum, apparently only on the label, first mentioned in print by (ieinitz in tiaca vonSaehsen (184;5), 

 p. I;M, without description, and lirst described and (igured by Giippert in 1SI8 (Nov. .\ct. Acad. Caes. Leop. 

 Carol. Nat. Cur., Vol. XXII, i>. 302, pi. x.xxviii, fig. Kj) from specimens .sent to him by Reich. Schimper 

 referred this also to Diooniles (Pal. VY'g., Vol. II, p. 211), but did not identify it with Kttingshausen's plant- 

 Professor Fontaine in his Potomac Flora, pp. 182, 184, al.so puts the Dioimites saxovinix (Reich) Schimp. in 

 the synonymy of this species, but apparently on the strength of two ligures of Ettingshausen (Siti-.b. Wicn. 

 Akad., Vol. LV, Abth. 1, pi. i, figs. 11, 12, p. 24.5) and the very imperfect fragment figured by Ilosius and von 

 der Marck from the Neocomian of Westphalia (Palaeontographiea. Vol. XXVI, pi. xliv, fig. 198). lie does not 

 seem to have seen Giippert's figures of Reich's Cenonninian plant . There is no certainty that the Westphalian 

 fragment belongs to that species. In view of this uncertainty and of the general improbability that the 

 species persisted into the Cenomanian, I shall not follow this course. If future investigation ever makes it 

 necessary the species must of course bear Keicli's name, which has priority over tliat of EttingshaiLsen by nine 

 years. — L. F. W. 



