732 PROF. A. DENDY AND MR. R. W. H. ROW ON 



Genus 6. Leucomalthe, Haeckel [1872] (emend.). 



Diagnosis. Colony individualised, with definite external form 

 and large central gastral cavity opening by a large single 

 osculum. Flagellate chambers greatly elongated, tubular, 

 copiously branched. Skeleton consisting of regular radiates, 

 large longitudinally placed oxea scattered throughout the 

 sponge body and not confiired to the cortex, and minute, 

 irregularly hastate microxea. 



For illustrations of this genus see Haeckel [1872]. 



The name Leucomalthe, originally applied to one of Haeckel's 

 subgenera, is retained for his Leucandra bomba, which presents 

 many peculiarities distinguishing it from the rest of the species 

 of that genus. Of these, the most important from the point of 

 view of our present classification is the very unusual type of canal 

 system figured by Haeckel, which shows a number of large and 

 very much branched flagellate chambers radiating from a central 

 gastral cavity. This is very diflerent from the normal leuconoid 

 canal system, and is fairly similar to that of Leucascus. On this 

 account, and on account of the regular ti-iradiates of the skeleton, 

 we have placed this species among the Leucascidse, though, it 

 must be acknowledged, on somewhat doubtful grounds, and the 

 peculiarities of its spiculation have necessitated the provision of a 

 special genus to receive it. 



The only known species is : — 



1. L. BOMBA Haeckel. 



Leucandra bomba Haeckel [1872]. 



Genus 7. Leucetta Haeckel [1872] (emend.). 



non Leucetta FolejaefF [1883]. 



non Leucetta von Lendenfeld [1891]. 



Diagnosis. Canal system leuconoid, with small, spherical or sub- 

 spherical flagellate chambers irregularly scattered through 

 the chamber layer. 



For illustrations of this genus see Haeckel [1872] and 

 Dendy [1913]. 



Haeckel [1872] proposed the genus Leucetta for calcareous 

 sponges with a leuconoid canal system and a skeleton composed 

 of trii-adiate spicules only, taking L. primigenia for his type 

 species. 



Pol^jaefi" [1883] abandoned Haeckel's classification, but re- 

 tained the name Leucetta in an entirely difl^erent sense, equivalent 

 to our Ljeucettusa, taking one of Haeckel's species, L. corticata, 

 for the type species of his genus. 



