46 
THE VOYAGE OF H.M.S, CHALLENGEE. 
Tetilla gravata, Hyatt. 
Tetilla gravata, Hyatt, Johnson’s New Universal Cyclopaedia, vol. vi. p. 1668, fig. 1, 1878. 
Sponge rounded, cylindrical, one or more large oscnles at the summit ; surface 
finely but densely hispid ; size, 100 mm. in height by 100 to 150 mm. in diameter. 
Spicules. — I. Megascleres. 1. Oxea fusiform, distal actine shorter and more 
abruptly pointed than the proximal; 2'0 by 0'016 mm. 2. Protrisene, rhabdome 3 '5 by 
O'Ol mm.; cladi 0'035 mm. long. 3. Trichodal protrisenes marginal to the pore-areas. 
4. Anatrisene, rhabdome 3*5 by 0‘006 mm.; cladi 0’04 mm. long, chord 0‘04 mm. 
II. Microsclere. 5. Sigmaspire, 0'013 mm. long. 
Habitat. — Buzzard’s Bay, Massachusetts, North America. 
Remarks. — This sponge is distinguished by its disproportionately small spicules; 
the cladomes of the trisenes are also much smaller than usual. There is a fine sjeecimen 
in the British Museum Collection ; this I have examined, but have not seen Professor 
Hyatt’s description ; for the reference to it I am indebted to the kindness of Professor 
A. C. Verrill. 
Tetilla geniculata, Marenzeller. 
Tetilla geniculata, E. von Marenzeller, Poriferen, &c., von Jan Mayen, 1886, p. 5, pi. i. fig. 4 
(published in Die Internationale Polarforschung, 1882-83, Die oester- 
reichische Polarstation Jan Mayen, Bd. iii.). 
Sponge', a fragment, bearing a single oscule, 4'0 mm. in diameter on its intact 
upper surface. 
Spicules. — I. Megascleres. 1. Oxea, 5‘0 by 0'03 mm. 2. Trichodal protrisene. 3. 
Protrisene with cladi of unequal length. 4. Anatrisene, rhabdome lO'O mm. and over in 
length. 
II. Microsclere. 5. Sigmaspire with a central spherical thickening of the spire 
(centrotylote) 0'013 mm. long. 
Habitat. — Jan Mayen, 191 to 216 fathoms. 
Remarks. — This species, which is fully described and illustrated by its author, is 
distinguished from all others of the genus by the characteristic centrotylote sigma- 
spires. 
Tetilla japonica, Lampe. 
Tetilla japonica, W. Lampe, Eine neue TetractineUiden form mit radiarem Bau.^ 
Sponge ellipsoidal ; bearing a single circular oscule at the summit ; produced into 
rooting filaments at the base ; surface hispid, with projecting spicules, raised into 
^ Inaugural Dissertation, 1886, pp. 1-18, pi. i. Eeprinted from the Archivf. Naturgesch. 
