PORIFERA. II. 



69 



sistency, the stalk firm, but flexible. The colour (in spirit) is a dirty eream-colour. The surface, both 

 of the stalk and of the outside of the calyx, is shaggy from projecting spicules. There is a thin 

 dermal membrane, which on the outside of the calyx is pierced by the projecting spicules. Pores and 

 oscida have not been seen with certainty; on the outside were seen scattered openings of different 

 sizes, and in one specimen there were a few openings in the bottom of the calyx; but in both cases 

 the question is possibly only of damagings of the soft tissue. 



The skeleton. The skeleton of the stalk consists of an axis of closely united needles parallel 

 to each other, between which are interwoven other needles which jut out horizontally. Above the 

 axis is divided more or less distinctly into fibres that pass into the skeleton of the calyx. In the 

 calyx-wall the skeleton consists of needles which are not united into fibres, and a great part of which 

 are placed chiefly in the longitudinal direction; they are not, however, parallel to each other, but inter- 

 cross irregularly, and some are also found placed in other directions. Between these needles spicules 

 and spicula-bundles are inserted on the outside, projecting through the surface and directed somewhat 

 upwards; the inside of the calyx, on the other hand, is smooth without projecting spicules. In the 

 upper part of the calyx-wall the spicules are closely packed and parallel to each other; in the refolded 

 edge spicules are found of a special size, as will be more particularly mentioned below ; moreover, this 

 edge is highly filled with chelse. Spongin is found, at all events in the stalk. 



Spicula •■: a. Megasclera. These are styli or subtylostyli; they fall under several forms which 

 also occur in different places of the sponge, but on account of the slight material, I have had some 

 difficulty in examining this fact. The skeleton of the stalk and the greater part of that of the calyx 

 consists of long, slender styli, which have sometimes a small head-swelling. They are fusiform, taper- 

 ing a little towards the head-end, and they have an evenly tapering, middle-long point. Downward 

 in the stalk they become shorter and also somewhat curved, and the spicules that are horizontally 

 interwoven in the stalk and projecting are all short and curved. In most individuals these projecting, 

 shorter, and a little curved needles deviate further by having a more or less distinct head, so that 

 they become tylostyli. Taken as a whole these styli vary from ca. 0-17— o-83 mm , but in the calyx and 

 the upper part of the stalk they do not generally go below ca. o-3 mm ; the thickness is 0-0057 — o-oii mra . 

 Besides these styli, which form, accordingly, the principal part of the skeleton, still two other forms 

 are found; the first of these are very slender styli, showing sometimes an almost imperceptible head- 

 swelling; they are considerably finer than the preceding ones, and they have a very long, fine point, 

 almost always with an even curve; their length is between 0-44— o-6 mm ; in their lower part they are 

 slightly fusiform, and their thickness in the thickest part is at most o-oo7 m "'. These spicules are found 

 outermost in the calyx-wall and project from it; they seem mostly, but not exclusively, to form the 

 projecting spicules. The third form of megascleres are short, straight tylostyli or subtylostyli; the 

 head is tolerably well marked and placed a little below the rounded end, the point is short. Their 

 length is 0-149 — o-22 mm , and the thickness is o-oo6 mm . These spicules are found in the refolded edge, 

 and they form the spiculation of this edge. These three forms of spicules, of which only the first- 

 mentioned form is very varying, while the two other forms are rather constant as to form and size, 

 do not appear to be connected by transitional forms, b. Microsclera. These are anisoehela; palmatae 

 and forcipes. 1. The anisochelse are Asbesloflluma-chelse of a structure characteristic of the sub- 



