3 



Die (jrriistl)il(tiiiiu; Uei U.liiK()]MKl(ii, l^lionulcii viv.. .'!2o 



Honiologieeii dor Vierstralilerteilp, rlos Saf^ittalringes uiul der Hasal- 

 locher, gezei^t zu haben. 



Haeckgl verhalt sich dem Problem der Nassellarienphylogenese 

 gegeniiber sehr reservierl. Zunachst woUea wir erwahnen, daW er 

 sich gegen cine polyphyletische Ableitung wendet : „T'olyphyIolio 

 hypotheses, doriving the different groups of Nassellaria from ditfereiit 

 skeletonless Nassellida, by development of simple siliceous skeletons 

 in ditt'ereut ways. Among the numerous polyphyletic hypotheses 

 which are possible, one of the simplest would be the supposition 

 that three different fundamental forms of skeleton may have arisen 

 independently one from another: (1) a simple sagittal ring as original 

 form of the Steplioidea and Spyroidea; (2) a simple basal tripod as 

 original form of de Plectoidea; (3) a simple latticed cephalis as origi- 

 nal form of the liotryodea and Cyrtoidea. This triphyletic hypothesis 

 is supported by R. Hertwig (1879, Organ, d, Kadiol., pg. 136); he 

 assumes that the original skeletonless Nassellida (Cystidium) have 

 produced three different branches, his ,,Acanthode8mida** (= Stephoidea 

 and Spyroidea) with a primary ring, his „Plagiacuuthida" (= Plec- 

 toidea) with a primary tripod, and his „Cyrtida" (= Botryodea and 

 Cyrtoidea) with a primary cephalis. This hypothesis seems rather 

 probable on the first view ; but it meets with the greatest difficulties 

 in view of the fact that these three original elements 

 of the skeleton are more or less evidently combined 

 in the great majority of Nassellaria"^). Wir stimmen 

 hierin mit Haeckel iibei'ein and sind durch das vorstehende Citat zu- 

 gleich der Miihe iiberhoben, auf Hertwig's Auffassung noch naher ein- 

 gehen zn miissen. Der Umstaud, dafi die verschiedenen Nassellarieu- 

 charaktere, die man zum Ausgangspunkt selbstandiger Stamme machen 

 kiinnte, meist kombiuiert auftreten, geniigt, um eine polyphyletische 

 Ableitung auszuschliefien. — Von monophyletischen Hypothesen stellt 

 Habckkl 3 zur Auswahl: 



„1 *). Monophyletic hypothesis, deriving all Nassellaria from a 

 latticed cephalis , a simple ovate or subspherical fenestrated shell 

 without ring and tripod (Cyrtocalpis, Archicapsa, etc.). This hypo- 

 thesis was given in 1862 in my Monograph, where I constructed the 

 first pedigree of Kadiolaria (p. 234). I there derived all the Cyrtida 

 from the Sphaeroidea (Cyrtidosphaera), supposing that Cyrtocalpis and 

 some other Monocyrtida may form a direct phylogenetical passage 

 from the Sphaeroidea to the Cyrtoidea. 



2. Monophyletic hypothesis, deriving all Nassellaria from a 

 simple sagittal ring (Archicircus, Lithocircus, etc.). This hypothesis 

 was stated by me in the years 1877 to 1879, when I had got the 



1) Challenger-Report, pag. 894. (Den letzten Passus habe ich 

 gesperrt drucken lassen.) 



2) Challenger-Report, pag. 893 — 894. — Die Reihenfolge der 

 Numerierung der 3 Hypothesen habe; ich in dem (!itat geaudert und 

 der historischen Reihenfolge angepaBt. Unser I., 2., 3. entspricht 

 dem 3,, 1,, 2. des Report. 



