REPORT ON THE TETRACTINELLIDA. 
343 
discotrisenes overlying desmas, flattened in a plane parallel to the surface, and also closely 
articulated. 
Palaeontologists used to distinguish such basal membranes as “ epitheca,” and several 
fossil species of Lithistids could be cited as resembling Discodermia nucerium in the 
presence of this membrane, as well as in the characters of the desmas and canal-system. 
Genus 5. Heterophymia, Pomel. 
Corallistidae with separate poriferous and oscular surfaces, which are distinguished 
by different ectosomal spicules, dichotrisenes occurring on the poriferous, and small, 
smooth, irregularly branched desmas on the oscular surface. 
Heterophymia heteroforynis (Bowerbank). 
Coscinosfongia lieteroformis, Valenciennes, MS. 
Dactylocalyx lieteroformis, Bowerbank, Proc. Zool. Soc. Lond., p. 85, pi. iv. figs. 1-4, 1869. 
Heterophymia lieteroformis, Pomel, Pal. de TOran, p. 143. 
„ „ Zittel, Abhandl. d. k. barer. Akad. d. Wiss., Bd. i. p. 121, 1878. 
Sponge. — Sessile, flabellate or foliate, sinuously plicated. Surface slightly undulating, 
minutely hispid. Oscules on the upper surface, slightly elevated and marginated, numerous, 
irregularly dispersed, 1 mm. in diameter. Pores congregated (in sieves 1 ), porous areas 
minute, slightly depressed, rarely more than their own diameter apart. 
Spicules. — •!. Megascleres. 1. Desmas, similar to those of CoraZ/fsfes. 2. Dicliotrisene, 
rhabdome long, curved ; cladi short, thick. This spicule is confined to the poriferous 
surface. 3. Strongyle, large. 
II. Microsclere (?). 
Colour. — Dark brown in the dried state. Size, 125 mm. high, 113 mm. broad; 
wall 8 mm. thick. 
Habitat. — Shanghai, China ; depth (?) (Collection of the Jardin des Plantes). 
Family III. Pleromida:. 
Genus 2 (?). Lyidium, 0. Schmidt. Incertse sedis. 
Lyidium torquila, 0. Schmidt. 
Lyidium tonpiila, 0. Scbmidt, Spong. Atlant. Gebiet., p. 84, woodcut, 1870. 
,, „ Zittel, Abbandl. d. k. baier. Akad. d. Wiss., Bd. i. pp. 103, 132, pi. i. fig. 10, 
1878. 
Sponge. — A fragment, probably of a flat plate-like individual, 3 mm. in thickness. 
Oscules and pores similar, large, 0‘5 to 1‘0 mm. in diameter, round simple openings of 
transversely directed canals situated on opposite sides of the plate. 
