REPORT ON THE TETRACTINELLIDA. 
283 
Colour. — Light yellowish-grey. 
Habitat. — Western entrance of English Channel; about lat. 48° 31' N., long, 10° 3' 
W. ; depth, 500 fathoms. 
Remarks. — From Carter’s description it is evident that this sponge is remarkably 
similar in the character of its tissues to Thrombus challengeri; the chief difference 
between the two species lies in the absence of amphiasters in the latter. 
Thrombus ornatus, n, sp. 
Sponge . — (?). 
Spicule. — 1. Trichotriaene, rhabdome cylindroconic, 0*065 mm. in length ; cladomc 
terminal, cladi curving gently forwards, outwards and backwards, protocladi 0*008 mm., 
deuterocladi 0*198 mm. in length, chord 0*055 mm., the esactinal rhabdome and the 
deuterocladi minutely, entirely, and erectly spined, the protocladi and ecactine smooth. 
Habitat. — Seychelle Islands. 
Remarks. — The spicule on which this species is founded occurs not uncommonly 
among the debris which Mr, Carter obtained from about the rooting spicules of Euplectella 
cucumer, and of which he was good enough to present me with a mounted slide. The 
difference between this trichotriaeue and that of Thrombus abyssi is to be found in the 
position of the cladome, which is not terminal in the latter species. 
Thrombus kittoni (Carter), 
Cortieium Icittoni, Carter, Arm. and Mag. Nat. Hist., ser. 4, vol. xiv. p. 24, pi. xv. fig. 48. 
Sponge. — Unknown, 
Spicule. — 1. Sigmatrisene, rhabdome short and stout; cladi varying from two to 
four in number, spreading upwards and outwards en fleur-de-lis ; both rhabdome and 
cladi thickly covered by stout, vertical, short spines, except near the cladal origin. 
Ehabdome 0*154 by 0*028 mm.; total length of spicule 0*268 mm. 
Habitat. — Colon, Panama. 
This species is founded on deciduous spicules from an “ arenaceous deposit,” so that 
it is presumably fossil. The description is taken from Carter’s account, but there seems 
to be some discrepancy between the text and the illustrations ; in the text the cladi 
are said to be twice the length of the rhabdome, while in the figure the reverse is 
represented. 
