SILICIOUS AND HORNY SPONGES WILSON. 297 



spinous, especially at the end (acanthtylaster) ; or, again, the rays 

 stoutly strongylate (strongylaster) ; oxy asters and small spherasters 

 with oxeate or strongylate rays may also occur. 



Sollas (1888, p. 195) restricts the genus to forms in which the 

 ectosome does not form a fibrous "cortex." Dendy (1905, pp. 

 80-81) gives sufficient reason for including both kinds of forms, 

 those in which the ectosome is not, or possibly is not, fibrous and 

 those in which it is more or less fibrous. This entails merging 

 Psammastra Sollas, covering species with a cortex (Sollas 1888, p. 

 200), in Ecionemia. 



Dendy (1916, p. 241) would exclude forms with trichodragmas, 

 assigning these to his new genus Rhabdodragma (1916, p. 239). 



Lendenfeld (1903, p. 61) makes Ecionemia a subgenus of Ancorina, 

 but extends the conception to include forms listed by Sollas under 

 several other genera. 



Lendenfeld (1906, p. 253) restores Ecionemia as a genus. He 

 would exclude forms with dichotriaenes, reserving Ancorina for the 

 reception of these. He would also exclude forms in which the 

 euasters are oxyasters, using Sanidastrella for these. Dendy (1905, 

 p. 81) on the contrary includes forms with dichotriaenes and forms 

 with oxyasters (1916, p. 242), a usage which seems to me necessary. 

 This being so, what remains to distinguish Ecionemia from Ancorina? 

 (1) The few recorded species of Ancorina have a well developed 

 fibrous cortex. This is less strongly developed or possibly absent 

 in the Ecionemia species. But this is not much of a reason for sepa- 

 rating the two groups. (2) The separation of the two genera nomi- 

 nally rests on the distinction drawn between the sanidaster of 

 Ancorina and the roughened microrhabd of Ecionemia. Lendenfeld 

 has consistently refused to recognize this distinction. And others, as 

 Dendy (1916, p. 239), think "the so-called sanidaster merges into 

 the microrhabd type of spicule." This would seem to be the case. 

 The sanidasters of the type species of Ancorina, A. cerebrum O. 

 Schmidt, are described by Lendenfeld (1894, p. 35) as 5-8 y. long 

 with numerous blunt spines, and such a spicule is certainly not far 

 from the microstrongyles of Ecionemia. Probably then Ecionemia 

 should even now be merged in Ancorina. 



ECIONEMIA CKIBROSA Thiele. 



Ecionemia (fibrosa Thiele, 1900, p. 31. 



Thiele's species is from Ternate. With it I identify a specimen 

 from Station D51T9. Lendenfeld (1903, p. 65) merges this species 

 in another of Thiele's species, E. agglutinans, also from the Moluccas, 

 but there is some difference in the records of the two forms. E. 

 cribrosa falls in the group of Ecionemia species in which small, 

 radial, ectosomal oxeas are present. 

 81709—25 3 



