HYALONEMA (PHIALONEMA) PATERIFERUM. 
365 
were chiefly observed by Wilson ( loc . cit.) in one of the specimens of form A, 
and by me in the specimen of form F. They probably occur in equal abundance 
also in the others, and in all they envelop the parts of the stalk-spicules lying 
just below the surface, within the body of the sponge. The stalk is preserved 
only in one of the specimens of form A. It consists here, according to Wilson 
(loc. cit.), of about fifty spicules, broken off below. 
The marginal pillules are diactine; the dermal, gastral, and canalar mostly 
pentactine, more rarely hexactine, and still more rarely diactine. I was unable 
to find any marked difference between the dermal, gastral, and canalar pinules. 
The slight difference in the length of the distal ray of the canalar and the other 
pinules, noticed by Wilson (loc. cit.) in the forms A and B, is not pronounced in 
the forms examined by me. I shall, therefore, in describing the pinules, not 
take their position into account. 
By far the most frequent form of pinule is a pentactine with rays of moderate 
length. In the other, much less frequent forms, a sixth (proximal) ray is devel- 
oped, or the distal or lateral rays are elongated, or the latter reduced to mere 
rounded knobs. The pentactine (and hexactine) pinules are connected by trans- 
itions with each other and with the large straight-rayed microhexactines. The 
pinules with well-developed proximal and reduced lateral rays appear as diac- 
tines. These are connected by transitional forms with the centrotyle amphioxes 
but hardly at all with the other pinule-forms. 
The pentactine or (rarely) hexactine pinules with a distal ray of moderate 
length (Plate 50 , figs. 6-8; Plate 52 , figs. 11-14) and well-developed laterals 
have a conical distal ray, very gradually attenuated to an exceedingly slender 
and sharp-pointed terminal cone. The distal ray is, in the pinules with moderate 
laterals, generally straight; in those with long laterals, which usually also have 
a long sixth proximal, and which appear as transitions to the microhexactines, 
often curved. The basal and terminal parts of the distal ray are smooth ; its 
central part bears small spines. The distal spines are always rather strongly 
inclined towards the tip of the ray. The proximal spines are either also so 
inclined (Plate 50 , figs. 6-8), or more divergent, often even vertical, or inclined 
slightly in the opposite direction (Plate 52 , figs. 11-13). The distal ray is in 
forms A and B, according to Wilson (loc. cit.), 100-220 m long, in form C 65-217 n, 
in form D 85-240 n, in form E 85-137 m, and in form F 93-220 yu. The basal 
and maximum thicknesses (together with the spines) of the distal ray are in forms 
A and B, according to Wilson (loc. cit.), base 5 m, maximum?; in form C base 
3-5 m, maximum 7-20 n; in form D base 2.5-5 n, maximum 3-22 m ; in form E 
