REPORT ON THE TETRACTINELLIDA. 
263 
II. Microscleres. 4. Sterraster, ellipsoidal, with three unequal axes, 0'09, 0'116, 
and 0'142 mm. in length respectively. 5. Somal spheraster, minute, centrum compara- 
tively large, actines short, cylindrical, truncate, from 0'004 to 0’007 mm. in diameter. 
6. Subcortical spheraster, centrum large, actines numerous, cylindrical, minutely spined, 
especially towards the ends, 0'0276 mm. in diameter. 7. Choanosomal chiaster, centrum 
small, actines slender, cylindrical, tylote ; 0’0236 mm. in diameter. 
Colour.— {!). 
Habitat. — Zlarin, Adriatic. 
Remarks. — The choanosome is crowded with foreign bodies, grains of sand, and the 
like ; and beneath the outer epithelium of the cortex the empty tests of Diatoms are 
accumulated as if to serve a skeletal purpose. The measurements given above were 
obtained from a part of one of Schmidt’s types presented to me by Professor von 
Graff. 
Cydonium tuberosum (0. Schmidt). 
Qeodia tuberosa, 0. Schmidt, Spong. Adriat. Meeres, p. 50, pi. iv. fig. 10, 1862. 
Sponge. — Irregularly tuberous ; surface finely hispid, with projecting megascleres ; 
cortex 1‘143 mm. in thickness, ectochrote very thin. Pores in sieves overlying incurrent 
chones. 
Spicules. — I. Megascleres. 1. Oxea, 3 '9 3 by 0'05 mm. 2. Orthotrixne, rhabdome 
3‘6 by 0'075 mm., cladi 0'31 mm. long. 3. Anatrisene, rhabdome 3'6 by 0‘023 mm., 
probably also longer, cladi OT mm., chord OT mm. long. 
II. Microscleres. 4. Sterraster, spherical, depressed, 0 ’09 mm. in diameter. 5. Somal 
pycnaster, actines cylindrical with truncate ends, 0*012 mm. in diameter. 6. Choano- 
somal oxyaster, actines conical, slender, roughened, variable in number, 0*023 mm. 
in diameter. 7. Subcortical spheraster, actines conical, minutely spined ; diameter 
0*02 mm. 
Colour. — Chalk- white in the dried state. 
Habitat. — Zlarin, Adriatic. 
Remarks. — The measurements were taken from a fragment of one of Schmidt’s types 
sent me by Professor von Graff. 
Cydonium normani, n. sp. 
Sponge. — Large, ellipsoidal ; surface thickly hirsute, owing to the projection of long 
spicules for about 25 mm. beyond it. Chones covered by sieve-like roofs. Oscules 
not distinguishable from the pores. Cortex consisting chiefly of the sterrastral layer. 
