KEPOET ON THE TETKACTINELLIDA. 
243 
0'054 mm. in diameter (B.), 0 063 mm. (S.), 0’06 mm. (R.). 5. Microstrongyle, minutely 
spined, centrotylote or not, 0'03 mm. long (B.), 0'0236 mm. (S.), 0'0316 by 0'005 
mm. (E.). 
Colour. — Slate-grey on the portion exposed to the light, almost white beneath ; 
specimens from considerable depths pink or red (Bowerbank). 
Habitat. — Rocks between high and low water mark, Torquay, Guliot Caves, south 
coast of Ireland (Bowerbank) ; near Plymouth, south coast of England (Stewart) ; Bud- 
leigh Salterton, Devonshire (Carter) ; the island of Douon, about four miles north-east of 
Roscoff, Brittany, at low water of highest spring tides (Sollas) ; St. Malo, Brittany 
(Grube). 
Remarlcs. — The letters given after the dimensions of the spicules signify as follows — 
(B.) measurements from Bowerbank’s description and figures ; (S.) from a specimen pre- 
sented me by Professor Stewart ; (R.) from a specimen obtained by myself from Douon, 
Roscoff. Bowerbank assigns certain specimens which he received from the Orkney 
Islands and Wick, Scotland, to this species, and I have made the same identification of 
specimens placed in my hands by Dr. Norman, and obtained by him from Kors Fjord, 
Norway. Further examination of these last has led me to regard them as the type of a 
new species, to be next described ; this helps to sustain the distinction which I have 
already suggested as existing between the sponge fauna of the North German Ocean and 
of the English Channel. 
The colour of the sponge is due to pigment-cells richly scattered through the cortex ; 
oil-bearing cells also occur in this region. 
Pachymatisma johnstonia, Hansen, appears to belong to a different genus. 
Pachymatisma normani, n. sp. 
Pachymatisma johnstonia^ Bowerbank (in part), loc. cit. 
„ „ Sollas, Ann. and Mag. Nat. Hist., ser. 5, vol. ix. p. 141, 
pL vi., 1882. 
„ „ Norman, Mon. Brit. Spong., Bowerbank, vol. iv. p. 28, 1882. 
Sponge. — Similar to Pachymatisma johnstonia, Bowerbank, but with a relatively 
thicker sterrastral layer in the cortex. 
Spicules. — I. Megascleres. 1. Strongyle, fusiform, curved, sometimes irregularly, 1‘68 
by 0’0276 mm. 2. Orthotrisene, rhabdome 0'83 by 0‘026 mm., cladi 0'446 mm. long. 
II. Microscleres. 3. Sterraster, ellipsoidal, 0'2 by 0'16 mm. 4. Oxyaster, actines 
few, conical, somewhat coarsely spined ; diameter 0’08 mm. 5. Microstrongyle, cylin- 
drical, minutely spined, 0‘019 to 0'022 mm. long. 
Colour . — Slate-grey in spirits, nut-brown when dry. 
