540 DR. W. A. CUNNINGTON ON THE 



The well-known genus Victorella, essentially a brackish and fresh- 

 water genus, is represented by the form V. symhiotica, a species 

 found associated with and growing through the sponge Spongilla 

 tanganyiJcce. Daring an expedition more recently undertaken to 

 the Birket Qarun in Lower Egypt, on which I was accompanied 

 by 0. L. Boulenger, farther specimens of a gymnola^matous 

 Polyzoon were collected, which were submitted to Rousselet for 

 examination. No definite report on these has been received, but 

 some of this material has evidently been transmitted by Rousselet 

 to other writei's on the Polyzoa, for Annandale (7, p- 107) records 

 his belief from an examination of the specimens, that the Qarun 

 species is identical with Victorella symhiotica fi'om Tanganyika. 

 Braem, on the other hand (53, p. 33), whilst affirming that the 

 forms Y. continentalis, V. hengalensis, a\id that from the Qarun 

 have close affinities with the European V. pavida, asserts that 

 " Rousselets V. symhiotica aus deni Tanganyika .... durch 

 einen abweichenden Baa des Darms ausserhalb dieses Kreises 

 steht " (Joe. cit. p. 34). 



Be this as it inay, there is a further matter concei'ning this 

 genus which demands considera,tion. The viQVf generally held by 

 specialists on this group has been that ViGtorella only recently 

 migrated from the sea into brackish and fresh- water. Braem, 

 however (63, p. 34), in the light of the Qarun specimens and the 

 species he describes from an inland lake in Turkestan, declares 

 his belief that on the contrary the genus is one which primitively 

 adapted itself to fresh- water conditions, and that the specimens 

 in question are " relict " forms. He considers that the existence 

 of the genus in Tanganyika further strengthens his supposition. 

 Since Tanganyika has been claimed by Moore as an undoubted 

 " Reliktensee," the true nature of this Polyzoon genus be- 

 comes a matter of some importance. Further light is fortunately 

 shed on this problem by the recent discovery by Harmer (99, 

 p. 45), in the Siboga material from the Dutch East Indies, of a 

 ti'uly marine species of Victorella. The usual view would thus 

 seem to be definitely supported, and the existence of- V. sym- 

 hiotica in Tanganyika, while of considerable interest, would not 

 tend to prove the occurrence in the lake of an ancient marine 

 fauna. 



The second gymnola^matous tj'pe — Arachnoidea ray-lanhesteri 

 — is certainly the most remarkable form from the African fresh- 

 waters. Despite I'ecent discoveries, it remains one of the few 

 instances known of a fresh-water incrusting gymnolaematous 

 Polyzoon, and is of peculiar interest accordingly *. In con- 

 sequence of its undoubted resemblance to the marine genus 

 Arachnidium., to which reference has already been made, Moore 

 (137, pp. 330, 332) regarded it as an important member of that 

 group of primitive mar-ine forms which, he contended, still exists 



* Another genus is Sislopia. 



