157 
towards the ends; varying from ca. 145—416//) in length, by 7— 
— 11,5 /f m thickness. 3. sigmata; evenly curved, sharply in- 
wardly bent points; rather constantly ca. 30 //. by 2 //,; in certain 
places in the choanosome between the fibres these sigmata are form- 
ing enormous heaps, but they also may appear in considerable 
numbers interwowen in the fibres between the megascleres. 4. 
rhaphides; very fine, thickest in the middle, evenly tapering to 
the awl-shapen points; ca. 50 fi hy \ rather uncommon. 
Genus Thrinacophora, Ridley. 
Thvinacophora dubia nov. sp. 
Coleridge Bay, Carnley Harbour. 25 f. Sandy mud. 4/XIL1914. 
Several specimens. Incrusting; forming thin, up to ca. 1 mm 
thick coatings over stones or the like (could not be stated with 
cerminty on account of the faet that the sponges were torn from 
their bodies of attachment; greatest extension ca. 30 mm; surface 
very finely hispid. Oscula? ostia? Colour pale dirty gray. 
Skeleton very confused. The long styli are lying in one plane, 
it IS parallel with the surface; most of them are running parallel 
with one another in two main directions, Crossing one another at an 
angle inelining towards 90®; but some, however a smaller part, 
are also lying in every other direction. The other spicules only 
in some places in their distribution show a tendency towards regul- 
arity; elsewhere they are lying quite disorderly. 
Spicules: (fig. 31a—c) 1. styli, smooth, varying through sub- 
tylostyli to tylostyli; all intermediate forms are found; often the 
swelhngs are situated at some distance from the basis of the shaft. 
All shgtly curved, tapering evenly to a very sharp point; thickest 
at the base or about the bending; varying in length from ca. 90// 
-2000 /., thickness up to 14 /.. 2. styli, slightly spined all 
over, curved, often strongly curved, at about the first fourth; but 
may be varying, thickest at the base, from here tapering evenly 
a most often tolerably sharp point which may however in a 
few cases be blunt. Length varying from ca. 100 // to 160 p by 
a thickness of ca. 4—5 p. 3. rhaphides, like rods, silicium- 
threads, often curved in more or less regular bows, semicircular 
