156 W. WOODLAND. 
33. Sottas, W. J.— The Sponge Fauna of Norway, etc.,” ‘Ann. Mag. Nat. 
Hist.’ (5), vol. ix, 1882, pp. 141, 426 (one-cell origin of the sterrasters 
of Pachymatisma johnstonia, the oxeotes and stigmata of 
Tetilla cranii, and the oxeotes, spherasters, grapnels, and other 
spicules of Thenea wallichii). 
34, “Challenger” Report, vol. xxv, ‘‘ Tetractinellida,”’ 1888 (one- 
cell origin of many spicules of the Choristida, the calthrops and 
rhabdus of the Lithistid desma, the spherasters of Tethya lyncu- 
rium, and the triens of Thrombus challengerii). 
85. ‘Encyclopedia Britannica,’ 9th ed., Article “Sponges,” 1891 
(one-cell origin of many of the spicules named in the four preceding 
references). 
36. Sottas, J. B. J.—“ On the Sponges collected during the ‘Skeat’ Hxpe- 
dition to the Malay Peninsula, 1899-1900,” ‘ Proc. Zool. Soc.,’ vol. ii, — 
1902 (siliceous globules in Tethya larva). 
37. VosMAER AND PEKELHARING.—“ Observations on Sponges,” ‘ Verh. Ak. 
Amsterdam’ (2), Bd. vi, 1898 (morphogenesis of the anisochela of 
Esperella syrinx). ; 
38. WreLTNER, W.—“Siisswasserspongien von Celebes (Spongillidenstudien),” 
‘Archiv f. Naturgeschichte,’ Bd. lxvii, Beiheft, 1901 (Maas’ account 
of the origin of the tylostyles of Tethya criticised). 
EXPLANATION OF PLATE 7, 
Ilustratng Mr. W. Woodland’s “Studies in Spicule 
Formation.” (VIII.) 
HEXACTINELLIDA. 
Figs. 3, 5, and 9 are from preparations of Rossella antarctiea, Ctr.; the 
remainder (figs. 1, 2, 4, 6,7, 8) are from R. podagrosa, Kpk. 
Fria. 1 (x 1600 diam.).—Young hexact stages of development. 1a repre- 
sents a hexact small in comparison with the enveloping syncytium. ‘The 
pink hue of the spherical mass of scleroplasm is due to the presence of 
numerous nuclei which, owing to imperfect preservation of the tissues, are 
not always visible individually. 
Fie. 2 (x 1600 diam.).—Microscleric monodiscohexaster ah somewhat 
dilated extremities. It is not certain whether the SATIRE have yet 
assumed their final form, but it is probable. 
