270 REVISION OF THE MONAXONID SPONGES, 1., 



specimens of Donatio). And, secondly, the examination of all 

 these specimens (some thirty in number), as well as many other 

 examples of the genus from Port Jackson and its vicinity, 

 resulted in my failure to discover any which accorded at all 

 satisfactorily with the description of any one of the species. As 

 a consequence, since it is practically certain that, with the 

 scarcely to be doubted exception of T'. muJtistella, all the species 

 in question are comprised amongst the specimens I have ex- 

 amined, I have deemed it best to regard definitely as the types 

 of these species in each case — T. multistella excepted — those of 

 the specimens labelled as representing them which best accord 

 with their respective descriptions. 



I have found the number of the rays of the spherasters to be 

 very constant in specimens of the same species, and have, there- 

 fore, attached importance to it as a specific character. The 

 precise number of the rays not being exactly determinable (owing 

 to their distribution over the surface of a sphere), I have stated, 

 in the following descriptions, only the number of them that can 

 actually be seen and counted. 



Tethya multistella. 



The " types," labelled as from Port Jackson, comprise three 

 distinct forms, which all resemble Tethya multistella in having 

 the surface subdivided into polygonal areas by pore-grooves, but 

 not one of which admits of being identified with either of the 

 varieties into which Lendenfeld divides the species. Some 

 further specimens, left Iw Lendenfeld and exhibiting a tessellated 

 surface, occur in the collection, labelled (wrongly so far as the 

 specific name is concerned) " Tethya fissurata, Port Molle '; and 

 these likewise are unidentifiable with T. multistella. As Len- 

 denfeld records the species from Port Jackson, Port Phillip, Port 

 Chalmers, and the Chatham Islands, it accordingly seems pro- 

 bable that his description of it was based solely on specimens 

 from one or other of the last-mentioned three localities, and that 

 the specific identity of the Port Jackson specimens with these 

 was merely assumed from their external resemblance thereto. It 

 is not unlikely that the true types of T. tnultistella are in the 



