HYALONEMA (PRIONEMA) PINULIFUSUM. 
285 
of Hyalonema ( Prionema ) azuerone, a large specimen of which was contained 
in the same bottle as the fragment of Hyalonema ( Prionema ) pinulifusum. I 
am therefore inclined to consider these pinules as spicules of the H. ( P .) azuerone 
which got into the H. (P.) pinulifusum accidentally. 
Of the three kinds of pinules which I consider proper to the sponge, the small 
ones with short and sparse spines on the distal ray are doubtlessly canalar. The 
two other kinds are probably dermal and gastral, but the fragmentary condition 
of the specimen renders it impossible to say which are which. In the follow- 
ing description I name these three kinds of pinules : — large pinules ; medium 
pinules; and small, canalar pinules, respectively. 
Pentactines have been found under various parts of the surface of the 
lamellae. Some hexactine and tylostyle megascleres and dense masses of diac- 
tine rhabds occur in the interior. The microscleres are numerous microhexac- 
tines, few micropentactines transitional between the microhexactines and the 
small canalar pinules, and amphidiscs. Of the latter seven kinds can be dis- 
tinguished : — macramphidiscs ; large and small mesamphidiscs with serrated 
teeth; large and small mesamphidiscs with smooth teeth; and large short- 
anchored, and small long-anchored micramphidiscs. 
The large pinules (Plate 70 , figs. 15-19; Plate 71 , fig. 11) are generally pent- 
actine, only very few hexactine ones having been observed. The distal ray 
is straight, fusiform, 200-400 /x long, generally 230-370 m, on an average 358 m, 
and 8-16 m thick at the base. Above it thickens very considerably and it 
measures, without the spines, 18-50 ^ in transverse diameter at the point of 
maximum thickness, which lies a short distance above the middle of its length. 
Farther on it again becomes thinner, and it ends in a rather broad and short, 
blunt- or sharp-pointed terminal cone. Its profile without the spines is elongate 
oval, drawn out at one end to the nearly cylindrical basal part and at the other 
to the terminal cone. The nearly cylindrical basal part and the distal cone are 
quite smooth, the remaining parts of it are covered with numerous large spines. 
The spines are usually all directed upwards and slightly curved, concave to the 
ray. The very lowest are quite divergent, the others strongly inclined, and in 
their end-parts nearly parallel to the adjacent part of the surface of the ray. 
Exceptionally (Plate 70 , fig. 19) some of the lowest spines are directed down- 
wards. The spines are generally 12-40 m long, 3-8 m thick at the base, simple, 
conical, and sharp-pointed ; they rarely bear one or two secondary spinelets on 
the outer, convex side. The maximum diameter of the distal ray, together 
with the spines, is 40-63 ^ . 
