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 

 Hoc. cit.), of about fifty spicules, broken off below. 



The marginal pinules 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 Hoc. cit.) in the forms A and B, is not pronounced in 

 the forms examined lay 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 //, 

 in form D 85-240 n, in form E 85-137 n, and in form F 93-220 fi. 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 n, maximum 7-20 ai; in form D base 2.5-5 n, maximum 3-22 yu; in form E 



