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grossern Annåkerung der Hydranthen; das ergiebt den Thujaria- 
und den Dynajnena-Typus, letzterer vielleicht zum Tlieil direet aus 
dem Sertularella-, zum Theil aus dem Thujaria- Typus ableitbar. 
Nock grossere Annåherung fiihrt zur Entwicklung der Pasythea- 
Gruppe, zum Theil von Thujaria , zum Theil von Dynamena aus; 
ferner zur Selaginopsis- und zur Hydrallmania- Gruppe, beide von 
Thujaria aus.“ When Schneider lets the joints disappear in 
order to produce the Dynamena- type, he forgets that according to 
his own definition of this type it is characterized by the possession 
of a joint between each two pairs of hydrothecae. 
Of the six groups into which Schneider divides the Ser- 
tulariidae we have already regarded Selaginopsis, and we sball 
later speak about Pasythea and Hydrallmania on mentioning the 
svstematic arrangement proposed by Professor Nutting. At this 
place, therefore, we have only to mention the groups Dynamena 
and Thujaria. 
Schneider characterizes the Dynamena-gronp in the following 
wav : „Die Hydrotheken opponirt, zwischen jedem Paar ein Gelenk; 
.; Mundung der Theca meist mit zwei vorgetåuschten (L e- 
vin s en) Zahnen, Deckel einfach. — Hierher gehoren: Diphasia 
rosacea L., attenuata Hincks, fallax Johns ton, pinaster Eli. 
et Sol., tamarisca L., pinnata Pallas., Sertularia pumila L., 
gracilis Hassall, operculata L.; Sertularia bispinosa Gray, 
minima Thompson, macrocarpa Bale.“ Of the species here 
nam ed Diphasia rosacea, D. attenuata, D . fallax, D. pinaster and 
D. pinnata have no teeth and an adcauline opercular val ve and 
belong to my genus Diphasia, while D. tamarisca must be referred 
to Sertularella as it possesses a tridentate hydrotheca and three 
opercular val ves. Sertularia pumila, S. gracilis and S. minima 
belong to my genus Sertularia, as the bidentate hydrothecae 
possess an adcauline collar and an abcauline opercular val ve, while 
Sertularia opercularis, S. bispinosa and S. macrocarpa inust be 
referred to a new genus, Odontotheca. 
