Ser Oe ea 
pitted surfaces. Canals obliterated. In one instance (fig. 11) 
there is a sharp bend in the upper portion of the spicule 
whilst the lower part is straight and pointed. The largest of 
these spicules is 2,9 mm. long by 0,13 mm. wide; the smaller 
form (fig. 12) is 0,94 mm. long by 0,067 mm. wide. In fig. 
13, the head is much larger in proportion to the length; this 
spicule is 0,832 mm. long by 0,15 mm. wide. All the 
forms are rare. 
Acuate spicules similar in form but usually so much 
smaller as to preclude a fair comparison are frequent in recent 
sponges from the Atlantic and have been placed by Mr. Carter 
under the genus Halichondria (Ann. and Mag. Nat. Hist. S. 4, 
Vol. XIV 1874, p. 16. Pl. XV, fig. 40 b, 41 b. — Vol. 18, 
Pl. XV. fig. 29). Oscar Schmidt also figures a similar form 
in Plocamia gymnagusa (Atlant. Spong. p. 62, Taf. 4, fig. 17b) 
and Sollas has also described like spicules in other species 
of the same genus (Ann. and Mag. Nat. Hist. July 1879 
p. 44, Pl. VI, fig. 3). Acuate spicules but with more deve- 
loped heads appear in the Haldon Green Sand (Ann. and 
Mag. S. 4, Vol. VII, Pl. X, fig. 77) and also from the upper 
Chalk at Coesfeld (Ueber Coelop. p. 37, Taf. V, fig. 1—10). 
There are two other forms of acuate spicules, in which 
the thickest portion of the spicule is just below the head and 
the spicule itself is straight and pointed (Plate I, figs. 14, 15). 
die arser is 1,22 mm, long by 0,112 ‘mm. wide, and 
resembles in form a spicule from Haldon (Ann. Vol. 7, Pl. X, 
fig. 78) and the smaller is 0,517 m.m. long by 0,56 mm. 
wide. 
Reniera, sp. 
(Plate eas.) 185) ro. 22). 
Spicules of a regular conical form, the thicker end evenly 
rounded and from this tapering either to a point or more fre- 
quently ending obtusely. In rare instances, the smaller end 
expands slightly, and the spicule becomes intermediate between 
