Knowledge of the Spongida. 111 
less among the white foreign bodies, becomes much darker 
in the dried sarcode internally where it is without them (No.1, 
reg. no, 71. 5. 12. 1, Brit. Mus.). 
TANTHELLA, Gray. 
This sponge is placed among the Pseudoceratida for having, 
like the foregoing, foreign bodies here and there in its fibre. 
The genus was first established by the late Dr. J. E. Gray 
(Proc. Zool. Soc. Lond., Jan. 14th, 1869, p. 49), although 
long before specialized by Pallas, followed by later authors 
under the names respectively of Spongia basta (“ Vox basta 
pannum grossius significat”) and SS. flabelliformis (see 
Gray l.c.). There are three thin specimens in the British Mu- 
seum under a glass case, bearmg my “running no.” 529. 
The central one, which is the largest, viz. Janthella flabelli- 
formis, Pall., registered ‘42. 6. 16. 5,” is fan-shaped, 11 x 9 
inches; and on either side are two others, one of which, bear- 
ing the name Janthella basta, Pall., has no number, and the 
other, called by Dr. Gray “Z. Homet,” is registered 57. 11. 
18. 200. The former of these two is vase-shaped, 8 inches 
high and 5 inches in diameter at the mouth, with a hole at 
the bottom, indicating that it also was fan-shaped first, and 
then, as usual, became converted into a vase-shape by approxi- 
mation and union of the opposite borders, except at the 
bottom, where the “ hole ’’ or incompleted union now exists ; 
the latter is but a flat, thin, fan-like fragment about 5x6 
inches in diameter. 
For this genus, as before stated, the late Dr. Gray proposed 
the name of “Janthella;”’ and the three specimens to which I 
have alluded, which are noticed in his paper under the names 
respectively of J. flabelliformis, I. basta, and I. Homet, are 
generically and specifically described; but there is nothing 
stated of their histological character, which character renders 
the genus as remarkable as it is unique among the Spongida, 
I allude chiefly to the composition of the fibre, in which the 
dark purple pigmental cells of the sarcode generally are so 
numerous in each horny lamina, that the latter not only appear 
to have been produced by them, but the fibre throughout, 
when viewed under the microscope by transmitted light, 
presents in colour one of the most beautiful objects that can 
be conceived, on account of the contrast between the clear, 
transparent, amber-looking horny lamine and the purple pig- 
mental cells in them, rendered bright carmine by transmitted 
light (Pl. 1X. figs. 12-14). 
All the specimens come from the Indian Ocean ; and they 
