EEPORT ON THE TETEACTINELLIDA. 
cliii 
Suborder I. HOPLOPHOEA. 
Lithistida provided with special ectosomal spicules, and usually with some form of 
microsclere. 
Demus I. Tri^nosa. 
Hoplophora in which the ectosomal spicules are some form of trisene, and in which 
microscleres (spirasters, amphiasters, or microrabds) are invariably present. The 
chamber-system is aphodal. 
Family I. Tetracladida: (Zittel). 
Tetradadina, Zitte], Abhandl. d. k. baier. Akad. d. Wiss., Bd. i. p. 100. 
Trisenosa in which the desma is tetracrepid. 
Genus 1. Theonella, Gray. 
Theonella, Gray, Proc. Zook Soc. Lond., p. 438, 1868. 
„ Zittel, Abhandl. d. k. baier. Akad. d. Wiss., Bd. i. pp. 103, 151, 1878. 
Tetracladidse with one or more simple oscules, pores in sieves generally distributed. 
Microsclere a microstrongyle. 
Type — Theonella swinhoei, Gray (p. 284). 
Genus 2. Discodermia, Bocage. 
Discodermia, Bocage, Journ. d. sc. math. pbys. et nat. Lisbonue, p. 160, pi. xi. fig. 1, 1869. 
„ Zittel, Abbandl. d. k. baier. Akad. d. Wiss., Bd. i. p. 151, 1878. 
Tetracladidse with differentiated oscular and poriferous surfaces ; the pores in sieves, 
the oscules numerous and simple. The microscleres are microxeas and microstrongyles. 
Tjrpe — Discodermia poly discus, Bocage (p. 330). 
Genus 3. Racodiscida, Zittel. 
Racodiscida, Zittel, Abbandl. d. k. baier. Akad. d. Wiss., Bd. i. p. 151, 1878. 
Tetracladidse with discotrisenes ; the microscleres are microrabds and spirasters ; the 
pores and oscules are simple. 
Type — Racodiscula poly discus (0. Schmidt) (p. 332). 
(ZOOL. CHALL. EXP. — PART LXIII. — 1888.) 
Err u 
