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 incUned 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 m long, generally 230-370 n, on an average 358 n, 

 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 Ues 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 cylinchical 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 sUghtly 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 /x 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 m- 



