54 Mr. W. J. Sollas on two new and 
of this group, it must now be known under the name of 
Crepidophyllum subceespitosum. The remaining forms origi- 
nally included under the title of H. subcespitosum are really 
referable to Heliophyllum, of which they constitute a separate 
species (H. elegantulum, Nich. & Thomson). The other form of 
Crepidophyllum is the large compound coral which was origi- 
nally described by Mr. Billings under the name of Diphyphyl- 
lum Archiact, but which turns out on microscopic examination 
to be unquestionably a species of Crepidophyllum. 

VII.—On Two New and remarkable Species of Cliona. 
By W. J. Souuas, M.A., F.G.S., &e. . 
[Plates I. & II.] 
1. Cliona mucronata (mihi). 
(Examined in the dried state.) 
Sponge occupying a number of chambers excavated in the 
solid calcareous base of a species of Isis. 
Chambers of various forms, oval, spherical, or irregular, 
joined together in a single series or in more complex groups 
by constricted apertures or by narrow stolon-like tubes, each 
of which is usually furnished with a spicular diaphragm. 
Spicules of three kinds :—1, a straight acuate (PI. IL. figs. 
1-3), having a cylindrical shaft, which terminates at one end 
in a more or less spherical head and at the other is rounded 
off bluntly and then produced axially into a short sharp spine 
or mucrone ; average length 0-004 inch, breadth across the 
head and rounded end 0°0006, and across the neck 0-0004, 
mucrone about 0°0002 inch long. 2, a slender pin-like acuate 
(Pl. Il. figs. 6,7), straight or curved, with a more or less 
spherical head and a sharp point; length 0°0073 inch, breadth 
across the head 0:0004, across the shaft 0°0002. 3, a minute 
or flesh-spicule (Pl. II. fig. 9), body spirali-sinuously curved 
once or oftener, or straight, irregularly spined ; length 0-0006 
inch. 
Diaphragms irregularly disciform (Pl. I. figs. 2, 3, 6), coni-" 
cal (figs. 5, 9), or tubular (figs. 4, 10) and open at both ends ; 
when conical, perforated by the truncation of the apex (fig. 5) 
or imperforate (fig. 9); circumferential edge of disk-like forms 
or the base in the case of the other two forms, attached to the 
walls of the containing tube or constricted aperture, across 
which the diaphragm extends transversely. Composed chiefly 
