434 Prof. VV. J. Sollas 07i the 



In 1880 Carter (xiv.) again refers to T. muricata, retracting 

 some of his previous statements, as when he admits the 

 specific value of the differences between T. WaUichn and 

 2\ muricata ; and he still rightly maintains the specific identity 

 of N. crassttj H. ])lacentula^ and E. compressa. 



Perhaps the most striking contribution made in this com- 

 munication to nomenclature is the attempt to impose Tisi- 

 phonia upon it, the claims of Thenea^ to say nothing of 

 Wyville-Thomsonia and Dorvillia, being wholly ignored. 

 Thenea has precedence of this MS. name by two years ; and 

 Wyville-TJwmsonia and Dorvillia were fully defined and 

 illustrated three years before the first figure of Tisiphynia^ 

 unaccompanied by generic diagnosis, was published in a 

 popular book. 



Finally, Oscar Schmidt (xv.), in a work bearing 1880 as 

 the date, also adopts the name Tisiphonia, and relies on its 

 rooting fibres as the characteristic feature by which it is dis- 

 tinguishable from Stelletta. If it were possible to establish 

 the genus on this character (and I am confident it is not), the 

 claims of Tisipthoiiia to recognition would not be enhanced 

 thereby, since with Thenea out of the way there would still 

 remain Wyville-Thomsonia and, perhaps with still stronger 

 claims, Dorvillia to be disposed of; and till genera are 

 named by one man's caprice this will not prove an easy task. 

 Again, if my contention so far should fail, then I will put in 

 argument the fact that the name T'isiphonia has already been 

 twice preoccupied, once by a butterfly [Tisiphone), and again 

 by a reptile {Tisiphone), and is therefore unavailable. 



But, finally, the generic value attributed by Schmidt to an- 

 choring filaments has no existence in the case in point. Amongst 

 ]\lr. jSorman's sponges there is a specimen of T. WalHchii, 

 which in no single feature differs from the ordinary type 

 except in one, that, namely, which Schmidt has come to regard 

 as of generic importance. No naturalist would make a different 

 species of it ; and yet it has the misfortune to be without an- 

 choring fibres. The distinction of Thenea from Stelletta is not 

 trifling ; it is sharp and obvious. The spicules of the two are, 

 it is true, similar, except that the former is characterized by a 

 spinispirule in place of a stellate; but this difference is just 

 as useful in classiflcation as that between the globate of Geodia 

 and the Stelletta stellate. The»real difference lies, however, 

 as Sir Wyville Thomson perceived in 1869, in the absence of 

 a crust in Thenea, which widely separates it from the Stelletta 

 series. Cither differences almost as great are also known — the 

 clear gelatinous character of the mesoderm, so different from the 

 grey granular mark of Stelletta, for one, and the vesicular 

 character of the water-canal system for another. 



