326 
THE VOYAGE OF H.M.S, CHALLENGER. 
Supplementary Account oe Species not contained in the Challenger Collection. 
Order LITHISTIDA, 0. Schmidt. 
Suborder I. HOPLOPHOEA. 
Demus I. Tria:nosa. 
Family I. Tetracladida: (Zittel). 
Genus 1. Theonella (Gray). 
Theonella jprattii (Bowerbank). 
Dactylocalyx prattii, Bowerbank, Proc. Zool. Soc. Lond., p. 89, pi. v. figs. 6-11, 1869. 
„ „ Carter, Ann. and Mag. Nat. Hist., ser. 4, vol. xii. p. 438, 1873. 
Theonella pratti, Zittel, Abhandl. d. k. baier. Akad. d. Wiss., Bd. i. pp. 103, 151, pi. i. fig. 95, 1878. 
Theonella swinlioei {pars), Carter, Ann. and Mag. Nat. Hist., ser. 5, vol. vi. p. 147, 1880. 
Sponge. — Irregularly cup-shaped, pedicelled ; surface even, slightly undulating. 
Oscules simple, small, dispersed, numerous. Pores in sieves. 
Spicules. — I. Megascleres. 1. Desma, epactines smooth, cylindrical, about 0’16 by 
0‘047 mm.; cladi short, rapidly breaking up into numerous syzygial tubercles; zygosis 
terminal; crepidial axis O'l mm. long. 2. rhabdome conical, strongylate, 
0*125 to 0*16 mm. in length; protocladi 0*09 to 0*13 by 0*032 mm., deuterocladi 0*14 
to 0*25 mm., cladal axis 0*032 mm. long. 3. Oxea, 0*006 mm. in diameter, length not 
ascertained. 
II. Microsclere. 4. Microstrongyle, straight, bacillary, surface roughened, 0*01 by 
0*002 mm. 
Colour. — Light brown, in the dried state. Size, 100 mm. in height ; major and minor 
axes of the brim of the cup 113 mm. and 88 mm. 
Habitat. — East Indies (?). Possibly from the Indian Ocean, off the coast of Hindustan. 
Remarks. — This sponge is distinguished from Theonella swinhoei by the characters of 
the excurrent canal-system, and also by the comparative minuteness of the microstrongyle, 
which also is straight in Theonella pratti, and usually curved in Theonella swinhoei, a 
distinction pointed out by Carter. 
Theonella ferruginea, Haeckel. 
Theonella ferruginea, Zittel, Abhandl. d. k. baier. Akad. d. Wiss., Bd. i. pp. 103, 151, pi. i. fig. 
9a, 1878. 
This species has not been described; it rests on an illustration given by Zittel 
{loc. cit.). 
