100 
THE VOYAGE OF H.M.S. CHALLENGEE. 
II. Microscleres. 3. Microxea, 0'115 mm. long; a smaller, centrally-thickened variety 
of this is also present. 4. Spiraster, passing into a metaster, 0’0316 mm. long. 
Co lour. — Y ello wish- white. 
Habitat. — Atlantic Ocean, near Cape. St. Vincent; depth, 292 fathoms. 
Remarhs. — Carter calls attention to the resemblance of the sjaicules of this sponge 
to those of Spliinctrella horrida, 0. Schmidt ; this suggested to me its relationship to 
Poecillastra, and, after carefully considering Carter’s description, I think it highly pro- 
bable that it belongs to this genus. The triod ap|)ears to represent the cladome of an 
orthotrisene, the rhabdome of which has been suppressed. 
Spliinctrella horrida, 0. Schmidt. 
Spliinctrella horrida, 0. Schmidt, Spong. Atlant. Gebiet., p. 65, pi. vi. figs. 6-7, 1870. 
Sponge. — A vertical plate, 2 to 3 cm. thick, with rounded edges ; surface rough ; 
oscules, the patent openings of oval elongated cloacas, fringed by a palisade of long 
spicules ; cloacas lined by a fenestrated membrane. 
Spieules. — I. Megascleres. 1. Oxea, 5‘0 by 0T42 mm. 2. Trisene, triradiate and 
quadriradiate ; a single actine 1'06 by 0T06 mm. 
II. Microscleres. 3. Microxea, with an irregularly swollen surface, 0'5 mm. long, 
and with a smooth surface, 0T8 mm. long. 4. Spiraster, 0'022 mm. long. 
Colour. — Ectosome blackish, choanosome colourless. 
Habitat. — Florida; depth, 111 to 228 fathoms. 
Sphinetrella annulata (Carter). 
Tisiphonia annulata, Carter, Ann. and Mag. Nat. Hist., ser. 5, vol. vi. p. 140, pL v. fig. 28, 1880. 
Sponge. — Massive, 2T2 mm. in diameter, attached. 
Spicules. — I. Megascleres. 1. Oxea, fusiform, 0‘885 by 0‘02 mm. 2. Calthroys, 
actines annulated by transverse, minutely spined, rounded ridges, each actine 0‘24 by 
0‘02 mm. 
II. Microsclere. 3. Spiraster, 0'0127 mm. long. 
Colour. — White. 
Habitat. — Gulf of Manaar. 
Remarhs. — Carter, in recognising the position of this species as one of the Theneidse, 
compares the calthrops (2) with the calthrops-like trisene of Normania crassa [Poecillastra 
compressa). But since, as he states, the microxea characteristic of Poecillastra is absent, 
it cannot be assigned to this genus. Still less can it be assigned to Thenea [Tisiphonia). 
The calthrops from its close resemblance to that which occurs in Spliinctrella ornata 
suggests the reference to Sphinetrella, to which genus I provisionally assign it. 
