SYM PAGELLA ANOMALA. 107 



is not iinifonn in the same hexaster but reaches up to 15/^. 

 Terminal disc, small, either rudimentary or convex with five, 

 distinct, marginal teeth. 



It now remains to consider the spiculation of the stalk, As 

 usual it is only the parenchymalia of this part of the sponge that 

 are synapticularly fused together. The thicker beams of the 

 rigid framework thus formed are beset with small prickles on 

 the surface. Superiorly in the stalk the ankylosis becomes confined 

 to the axial portion and finally ceases to exist before the body 

 proper is reached. 



In the upper part of the stalk the dermalia and the hypo- 

 dermalia exhibit essentially the same characters as on the body ; 

 only they are both more closely set together. Towards the basal 

 end, the dermalia change their character very considerably (fig. 

 6). They are here small regular hexactins in which all the six 

 rays, being beset all over with nearly vertically outstanding- 

 prickles, are alike in appearance ; they can not therefore be 

 called pillules. 



Besides the usual onychaster-like hexaster and the strobilo- 

 plumicome, there occur with tolerable frequency in the stalk 

 certain discohexasters which seem to be p)eculiar to it (figs. 17- 

 19). These vary considerably in size and general appearance. 

 A large specimen (fig. 17) of them may have a diameter of 90 ,". 

 Each short principal is supplied with 2 or 3, sometimes 4, rough- 

 surfaced, diverging terminals, which perceptibly thicken towards 

 the small, convex, terminal disc with 5, recurved, marginal teeth. 

 Smaller specimens (figs. 18 and 19) of the same may be so small 

 as to measure only 30 ,« in diameter. While diminishing in size, 

 the terminals become more slender in caliber while the number 



