41. {No microscleres. Megascleres tylostyles with or without styles { _Suberites_ {Microscleres centrotylote. Megascleres styles or tylostyles { _Ficulina_ 42. {Choanosomal megascleres smooth 43 {Choanosomal megascleres spined _Dendoryx_ {Microscleres chelae and sigmata of about the same size 43. { _Lissodendoryx_ {Chelae, if present, smaller than the sigmata _Yvesia_ 44. {Isochelae{225} _Esperiopsis_ {Anisochelae _Esperella_ 45. {Fibres or columns plumose 46 {Fibres or columns ectyonine 47 46. {Microscleres toxa _Ophlitaspongia_ {Microscleres absent _Axinella_ 47. {Skeleton reticulate 48 {Skeleton not reticulate 49 {Microscleres present. Spicules of the fibre core spined _Myxilla_ 48. {Microscleres absent. Spicules of the fibre core smooth { _Lissomyxilla_ 49. {Main skeleton formed of plume-like columns 50 {Main skeleton formed of horny fibres (ectyonine). Special dermal { skeleton wanting _Clathria_ {Dermal skeleton contains styles only _Microciona_ 50. {Dermal skeleton contains diactine spicules with or without styli { 51 {Main skeleton columns with a core of smooth oxeas 51. { _Plumohalichondria_ {Main skeleton columns with a core of spined styles _Stylostichon_ {Central axis contains much spongin. Echinating spined styli { present _Raspailia_ 52. {Central axis with little or no spongin. Spined styles absent. { Pillars radiating from the axis support dermal skeleton { _Ciocalypta_ 53. {Ground substance between chambers clear; chambers pear-shaped { or oval; eurypylous _Spongelia_ {Ground substance granular. Chambers spherical with aphodi 54 54. {Fibres not pithed; sponge fan-shaped _Leiosella_ {Fibres pithed; sponge massive _Aplysina_