ANTARCTIC SPECIES OF TEDANIA 345 



discoid specimen, with spicules of small size, which was to all intents a specimen of 

 T. teniiicapitata, but which was found to contain embryos typical of T. massa. Top- 

 sent's (1908, pi. i, fig. 3) T. charcoti might be 

 placed in the area where T. murdochi and T. char- 

 coti overlap. And so on. As will be seen from 

 the diagram, T. spinata and T. tenuicapitata, 

 T. mossa and T. spinata, and T. murdochi and 

 T. charcoti can only be confused in external form, 

 and T. spinata and T. murdochi resemble each 

 other only in spiculation. On the other hand, T. 

 temdspiculata, T. charcoti and T. massa are sub- 

 ject to considerable confusion. 



The second point raised is that concerning the 

 specialized character of these species as compared 

 with the remaining species of Tedania} 



Judging from the embryological evidence, and 

 the development of the external form and spicu- 

 lation, Tedania nigrescens (Schmidt) is the most 

 primitive species of the genus, and the Antarctic 

 group, including also T. mucosa, Thiele, T. ex- 

 cavata, Thiele, T. pectinicola, Thiele, T. fuegiensis, 

 Thiele, and T. infundibuliformis, Ridley and Dendy, 

 is the most specialized. And of these, the species 

 found in the Antarctic {sensu stricto) are the most 

 highly specialized of all. Thus, in T. oxeata the 

 styli are replaced by pseudoxea (cf. the life history 

 ollophon radiatus, Topsent (Burton, 1931, p. 514, 

 fig. 2e)); T. charcoti shows a higher degree of 

 development than the others, since the fully- 

 developed embryonic spicules are styli ; but in T. massa is found the most convincing 

 proof that the Antarctic species are more specialized than the non-iVntarctic. In 



^ The section Tedanieae, of the Desmacidonidae, consists at present of the genera Tedania, Gray ; Trachy- 

 iedania, Ridley; Tedaniopsis, Dendy; Paratedaiiia, Burton; Tedaniella, Czerniavsky ; and Tedanione, Wilson. 

 As shown on p. 306, Trachytedatiia must be regarded merely as representing the post-larval stage of 

 Tedania spinata (Ridley) and perhaps others. Further, Tedaniopsis and Paratedaiiia are clearly synonyms 

 and, as shown on p. 306, the genotype of the latter is synonymous with Tedania massa, Ridley and Dendy. 

 Tedanione, on the other hand, appears to be synonymous with Rhaplioxya, one of the Axinellidae, and 

 Tedaniella, inadequately characterized, may be a synonym of Petrosia. 



The species of Tedania, as here understood, appear to number 24: T. bispinata, Hentschel; T. charcoti, 

 Topsent; T. commixta, Ridley and Dendy; T. {Tedanione) connectens (Brondsted); T. coralUophila, Thiele 

 (with T. brez'ispiculata, Thiele; T. maeandrica, Thiele; and T. 7'eticulata, Thiele, us probable synonyms); 

 T. diraphis, Hentschel; T. diversirhaphidiophora, Brondsted; T. excavata, Thiele; T. fragilis, Lambe; 

 T. fuegiensis, Thiele ; T. infundibuliformis, Ridley and Dendy ; T. massa, Ridley and Dendy ; T. mucosa, 

 Thiele; T.inurdochi, Topsent; T. nigrescens {^tchmidt) (see Burton and Rao, 1932, p. 353, for full synonymy); 



500n 



400- 



300 



200- 



lOO-l 



BOO 



700 



600 



500 



400 



300 



200 



Fig. 43. Showing the relative lengths of the 

 styli and tornota in: a, T. spinata; b, T. mur- 

 dochi; c, T. tenuicapitata; d, T. charcoti; 

 e, T. massa. 



