143 
Spicules: (fig. 21a —d) 1. styli, slightly bent, densely and 
rattier coarsely spined all over, spines stoutest at the base; the 
bending, which is very even, as a rule takes place about the’first 
third, but may be situated just at the base and beyond the middle 
The base of the spicule thickest, from here tapering towards the 
Sharp point. Length varying from ca. 90—140 p, thickness up to 
8 //. Many developmental stages. 2. tornota, smooth; in most 
cases straight, only a little thicker at the middle; the sharp points 
aiways very abruptly marked off; length 130-156 rather con- 
stantly 154 thickness only ca. 4 /c ; they are found in a much 
smaller number than the styli. 3. sigmata; rather evenly curved 
except the ends, which are bent rather sharply inwards, almost 
aiways somewhat contorted. Size rather constant, varying about 
32 fi by a thickness of 2 ft,. 4. isanchorae, with three ident- 
cal teeth at both ends; shaft evenly curved and of the same thick- 
less in the whole length. Teeth, slightly curved, are projecting from 
he shaft at a rather acute angle; if front teeth were prolonged 
o as to meet one another, they would forme a curve quite sym- 
netrical with that of the shaft; lateral teeth easily seen in side 
lew (of the spicule) but with difficulty in front view, on account 
f their insignificant thickness but comparatively great breadth; 
mgth of teeth ca. 2'/s the breadth; rounded at the ends. Length 
f isanchorae very much varying, from ca. 10—26 ft. 
Genus Clathria, O. Schm. 
Clathria Mortensenii nov. sp. 
Perseverance Harbour, Campbell Island. 20 f. Sandy mud. 10/XII.1914. 
Incrusting on a shell. Greatest thickness 2 mm. Surface densely 
tepid by spicules piercing the dermal membrane perpendicularly; 
hs latter thin, covers small subdermal-cavities. Oscula scattered 
i out; in one place, however, 10 close to one another in a single 
i'W, they are 0,3 mm in diameter. Ostia numerous. Ca. 0,io mm 
I diameter, in several places more or less tightly shut up. Con- 
=4ence rather firm, somewhat elastic. Colour dirty gray. 
: Skeleton composed of only slightly developed and rather ill de- 
tied skeleton-fibres, which are passing from surface of attachment 
