Note on Astrosclera willeyana Lister. 



579 



53. Graham Brown, T., ' Quart. Journ. Exper. Physiol.,' 1910, vol. 3, p. 319. 



54. „ ibid., 1911, vol. 4, p. 19. 



55. „ ibid., 1911, vol. 4, p. 151. 



56. Maciesza, A., and Wrzosek, A., 'Arch. f. Rassen- u. Gesellschafts-Biol.,' 1911, vol. 8, 



p. 1. 



57. „ „ ibid., 1911, vol. 8, p. 145. 



58. „ „ ibid., 191 1, vol. 8, p. 438. 



59. Graham Brown, T., ' Quart. Journ. Exper. Physiol.,' 1911, vol. 4, p. 273. 



60. „ ' Eoy. Soc. Proc.,' 1911, B, vol. 84, p. 308. 



Note on Astrosclera willeyana Lister. 

 By K. Kirkpateick. 



(Communicated by S. F. Harmer, F.E.S. Eeceived December 14, 1911, — Eead 

 January 18, 1912.) 



(Printed by permission of the Trustees of the British Museum.) 



As the result of an investigation of 47 specimens of Astrosclera willeyana 

 dredged by me off Christmas Island, Indian Ocean, I have found that this 

 organism is a Siliceous Ectyonine Sponge with a supplementary skeleton of 

 aragonite. The sponge owes its unique character to the fact of its being 

 associated with a degenerate Floridean Alga. Sponge cells capture and 

 envelop the algal tetraspores and carpospores and secrete around them 

 concentric layers of aragonite. The spherules so formed are in many respects 

 comparable with the cyst-pearls of Mollusca. Just as certain Ectyonine 

 sponges make supplementary skeletons out of foreign particles of sand, 

 Foraminif'era, etc., so Astrosclera builds a similar kind of skeleton out of the 

 spherules. The alga probably comes under the Ceramiales Oltm., and appears 

 to belong to a new genus and species, of which a provisional diagnosis is 

 given below : — 



Bhoclocliplolia* n. gen., Alga degenerata, in spongia (scilicet Astrosclera 

 willeyana Listeri) symbiotica, partim in carne, partim in calcis sceleto duro 

 sita. 



Thalli plantarum sexualium minimi, et in spongise carne viventes. 

 Thallus $ carpogonia binis trichophoris et trichogynis ornata, thallus J 1 

 antheridia ramosa gerens. 



Thallus asexualis in calcis sceleto duro perterebrans simulque in carne 



* pobo (in comp.), red (alga) ; bvrr\6os, double ; /3tos, life ; referring to the habitat in 

 the solid calcareous skeleton, and in the soft tissues of the sponge. 



