230 AETHUB DENDY. 



very natural and well-characterised genus, comprising only 

 three species, viz. S. primitiva, S. sagittifera, and S. 

 conifer a, all of which are described by Haeckel in his great 

 monograph. 



Genus 3. — Sycon (Risso, emend.), figs. 2 — 8. 



Diagnosis. — The radial chambers are usually more or less 

 united at places where they come into contact with one another, 

 and they are always crowned at their distal extremities with 

 tufts of oxeote spicules. 



Remarks. — The most characteristic feature of this genus 

 is afforded by the tufts of oxeote spicules which crown the 

 distal ends of the radial chambers. In some species, such as 

 Sycon boomerang (4) and S. gelatinosum (4, 5), we find 

 a transition to the genus Grantia, in the presence of a pore- 

 bearing dermal membrane stretched between the distal ends 

 of the radial chambers; but this never forms a cortex which 

 completely covers over the chambers as in the Grantidae, and 

 it in no way interferes with the characteristic tufts of oxeote 

 spicules. 



The genus as here constituted includes most of Haeckel's 

 species of his genus Sycandra (5), but I follow Polejaeff" (8) 

 in giving priority to the old name Sycon. Familiar European 

 examples are S. raphanus and S. ciliatum, and I also 

 include S. (Grantia) compressum, on account of the tufts 

 of oxeote spicules which crown the ends of the chambers. 

 Polejaeff^s genus Sycon is, as already pointed out, more com- 

 prehensive, and includes our Sycetta, while von Lendenfeld 

 (10) adopts the genus Sycandra in almost the same sense as 

 Haeckel. 



Genus 4. Sycantha, von Lendenfeld (10). 



Diagnosis. — Radial chambers united in groups, with 

 freely projecting distal cones surmounted by tufts of oxeote 

 spicules. 



Remarks. — It appears to me that the only character which 

 can be relied upon for distinguishing this genus is the grouping 



