REPORT ON THE TETRACTINELLIDA. 
61 
II. IVIicroscIere. 5. Sigmaspire, 0'0625 mm. long. The sigmaspires are spined on 
the outer side and at their extremities ; they are also three to four times as large as 
those of most Tetillidse. 
Colour. — Purplish-black. 
Habitat. — Unknown. 
Remarks . — The cortex of this remarkable sponge is that of a genuine Craniella, it 
measures about 1‘2 mm. in total thickness, the outer layers, with the usual characters of 
Craniella, being about 0’9 mm., and the inner layer with widely extending subdermal 
cavities about 0'3 mm. across. Carter represents the natural surface of a half of 
the sponge, which in the entire state was approximately spherical ; apparently it had 
been bisected, one half sent to Carter to describe, and the other retained in the 
British Museum collection ; the two halves are now placed together with a common label. 
The gigantic spined sigmaspires are quite sufficient to characterise the species. 
Craniella cranium, auctt. 
Alcyonium cranium, Miill., Zool. Dan., pi. 85, fig. 1, 1789. 
Tetliya cranium, Lmk., Mem. d. Mus., vol. i. p. 71, 1815. 
Alcyonium cranium, Lmx., Hist. d. Polypes, p. 347, 1816. 
Spongia pilosa, Mont., Mem. Wern. Soc., vol. ii. p. 119, pi. xiii. figs. 1-3, 1818. 
Teihya cranium, Elem., Brit. Animals, p. 519, 1828. 
,, ,, Blainv., M4m. dAct., p. 544, 1834. 
Tethea cranium, JoLnst., Brit. Spong., p. 83, pi. i. figs. 1-8, 1842. 
„ „ Bwk., Mon. Brit. Spong., vol. i. p. 182, pi. xxxi. fig. 362, 1864. 
„ „ Bwk., Mon. Brit. Spong., vol. ii. p. 83, 1866. 
Tetliya cranium, 0. Sch., Spong. Adriat. Meeres, Suppl. ii., pi. i. fig. 14, 1866. 
,, „ Gray, Proc. Zool. Soc. Bond., p. 543, 1867. 
,, „ Carter, Ann. and Mag. Nat. Hist., vol. viii. p. 104, 1870. 
„ „ Carter, Op. cit,, vol. ix. p. 419, pi. xxii. fig. 9, 1872. 
,, unca, Bwk., Proc. Zool. Soc. Bond., p. 118, pi. v., 1872. 
,, cranium, Bwk., Mon. Brit. Spong., vol. iii. p. 315, pis. xiv., Ixxxix., 1874. 
Tetilla cranium, Miill., and Craniella cranium. Soil., Ann. and Mag. Nat. Hist., vol. ix. p. 149, 
pi. vii., and p. 327, 1882. 
Tethya cranium, var. typica, Norman, Bwk., Mon. Brit. Spong., vol. iv. p. 39, 1882. 
Tetilla cranium, Hansen, Norske Nord. Exped., Spongiadae, p. 18, pi. v. figs. 3, 4j pi. vii. 
fig. 16, 1885. 
Craniella mulleri, Vosmaer, Sponges of tke “Willem Barents” Expedition, p. 6, pi. ii. 
figs. 9-15; pi. V. figs. 1, 2, 1886. 
Non Tetilla cranium, 0. Sch., Spong. Atlant. Gebiet., p. 63, 1870. 
Spicules. — I. Megascleres. 1. Somal oxea, anisoactinate, distal actine thicker than 
the proximal, which is attenuated to an almost filiform termination, 2T by 0'05 mm. 
(Bwk.), 218 by 0‘027 mm. (Soil. N)., 4'28 by 0‘05 mm. (Soil. C.). 
2. Cortical oxea, 0'83 by 0'038 (Bwk.), 0‘9 by 0'032 mm. (Soil. C.). 
