440 
THE VOYAGE OF H.M.S. CHALLENGER. 
Tethya (?) stellata, 0. Sclimidt. 
Cometella stellata, 0. Sclimidt, Spong. Atlant. Gebiet., p. 49, pi. iv. fig. 10, 1870. 
Tethya cometes, O. Schmidt, Spong. Meerb. Mexico, p. 78, 1880. 
Sponge. — A spherical body supported by a long slender stalk, surface raised into 
numerous rounded papillae, so that the whole sponge resembles a stalked mulberry. 
Spicules . — I. Megasclere. 1. Strongyle, sometimes fusiform, sometimes cylindrical. 
II. Microscleres. 2. Somal spJieraster, as in Tethya lyncurium. 3. Radical spher- 
aster, smaller, and distinguished by longer, often tuberculate actines. 
Habitat . — Cuba ; depth, 317 to 344 fathoms ; also lat. 24° 8' N., long. 82° 51' W., and 
lat. 23° 13' N.,long. 89° 16' W.; 84 to 329 fathoms. 
Tethya mam, Selenka. 
Tethya maza, Selenka, Zeitscbr. f. wiss. Zool., Bd. xxxiii. p. 472, pi. xxviii., 1879. 
Sponge. — Spherical, attached ; surface conulose, conules gemmiferous. Pores in 
sieves leading into extensive intercortical cavities. Oscule single, situated at the 
summit. Cortex differentiated into an outer and inner layer. 
Spicules . — I. Megasclere. 1. Strongyloxea, of the usual form in the genus, 1'68 by 
0*032 mm. 
II. Microscleres. 2. Cortical Spheraster, of the usual form, but characterised by 
very variable actines, sometimes conical and oxeate ; they are more frequently conical 
and strongylate, and then usually bear one or more spines, or they may dichotomise. 
3, Somal chiaster, as in Tethya seychellensis, E. P. W., 0*0118 mm. in diameter. 
4. Choanosomal chiaster, of excessively variable form ; actines usually few, six or 
seven in number, slender, cylindrical, roughened rather than distinctly spined ; very 
rarely dichotomose ; centrum usually absent; total diameter 0*0237 mm. 
Colour . — Orange-yellow when alive, in spirits greyish- white. 
Habitat. — Bay of Rio Janeiro, between tides (Selenka). 
Remarhs. — Through the kindness of my colleague. Dr. E. P. Wright, I have been 
able to examine typical specimens of this sponge. Its distinction from Tethya seychel- 
lensis, E. P. W., rests entirely on the difference in form of the choanosomal aster. 
Budding, according to Selenka, takes place during the winter season, but not con- 
tinuously ; the buds originate in the cortex, and in such numbers as to almost obliterate 
the intercortical cavities. They then glide out along one of the spicular fascicles of the 
conules, and remain attached till their development is nearly complete, when they drop 
off. The oscule and subcortical cavities are not developed till after complete separation 
from the parent. 
