[250]

Topsent, Arch. Zool. Exp. (3) viii. 1900, p. 36.

[251]

Sollas, Challenger Monograph, xxv. pt. lxiii. 1888, p. lxxxix.

[252]

Topsent, Arch. Zool. Exp. (3) viii. 1900, p. 226. For an account of certain very remarkable structures termed diaphragms in Cliona mucronata and C. ensifera, see Sollas, Ann. Mag. Nat. Hist. (5) i. 1878, p. 54.

[253]

R. von Lendenfeld, Monograph of Horny Sponges, 1889, p. 831.

[254]

Cf. Minchin in E. Ray Lankester's Treatise, p. 77.