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sesses an adcauline operculum and a horizontal margin, characters 
which have not been found in any Thujaria. Broch has already 
pointed out that it must be referred to Diphasia. To the latter 
genus I am also inclined to refer Th. elegans Krp. Th. ramosis- 
simci Allm. and Th. plumosa Clark belong to my new genus Odon- 
totheca, and I shall later show that T. plumulifera Allm . x ) belongs 
to the genus Hydrallmania. However, a fragment sent to me by 
Prof. Nutting under the name of Th. plumulifera does not 
belong to this species, but to a new species of the genus Sertularia. 
Pasythea (Lamour.) Nutting. 
This highly artificial genus is at present represented by three 
species, namely P '. qvadridentata Eli. & Sol., P. hexodon Bale and 
P. philippina Markt. The first, which is a Sertularia, is nearly 
related to S. pumila, the second, of which I have examined a 
colony from Singapore, is a Thujaria with a si milar form of 
aperture to that found in Th. desmoides, Th. lichenastrum and Th. 
fruticosa, and the original specimen of the third which I have had 
on loan from the Zoological Museum of Vienna is a young colony 
of Idia pristis. That neither the colonial characters are constant 
is evident from some observations made by Bale 2 ) who says about 
specimens of P. qvadridentata from Bondi: “The Bondi specimens 
are peculiar, a considerable proportion of the internodes bearing 
only a single pair of calycles each; indeed some of the shoots 
are so arranged throughout, and thus differ in no respect from a 
typical Sertularia .” Eurther he says about the hydrothecæ of 
P. hexodon 3 ): “In most cases those on the two sides of the 
hyarocaulus are opposite to each other, but it is quite common to 
find them alternate, and the set frequently contains more on one 
side than the other, as three to four, or four to six. 
) I have examined a fragment of the original specimen, sent to me from 
the Museum of Comp. Zoology, Cambridffe 
2 ) 8, p. 770. 
3 ) 8, p. 771. 
18 * 
