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THE VOYAGE OF H.M.S. CHALLENGER. 
Genus 10. Tethyopsis, Stewart. 
Tethyopsis, Stewart, Monthly Micr. Journ., N.S. vol. x. p. 281, 1870. 
Sponge more or less spherical, produced into a complex cloacal tube, the mega- 
scleres of which are anisocladal orthotrisenes. The microscleres are an ectosomal 
spheraster (very minute pycnaster), a choanosomal chiaster, and an orthodragma ; sanid- 
asters are absent. 
The pores are not distributed over the general surface of the Sponge. 
Type — Tethyopsis columnifera, Stewart (p. 190). 
Genus 11 . Disyrmga, n. gen. 
Sponge more or less spherical, produced at one pole into a complex cloacal tube, and 
at the opposite pole into a simple poriferous tube, to which the pores of the Sponge are 
confined. The megascleres of the cloacal tube are modified ortho- and dicho-trisenes. 
The microscleres are an ectosomal sanidaster, a choanosomal oxyaster, and an ortho- 
dragma. 
Type — Disyringa dissimilis (Ridley) (p. 161). 
Genus 12. Stryphnus, Sollas. 
Stryphnus, Sollas, Sci. Proc. Roy. Duhl. Soc., vol. v. p. 193, 1886. 
Sponge massive; ectosome consisting of collenchyma densely crowded with mega- 
scleres irregularly arranged. The somal megascleres are colossal oxeas, irregularly 
distributed. The ectosomal megascleres are ortho-, plagio-, or dicho-trisenes. The micro- 
scleres are some form of euaster and an irregular sanidaster or amphiaster. 
Type — Stryphnus niger, Sollas (p. 171). 
Subfamily 4. Ehabdasterina. 
Genus 13. Ecionema (Bowerbank). 
Edonema, Bowerbank, Mon. Brit. Spong., vol. i. p. 173, 1864. 
The ectosome does not form a cortex. A microrabd is present in addition to a 
euaster. 
Type — Ecionema acervus, Bowerbank (p. 196). 
