86 



PORIFERA. I. 



scattered spicules. Spongtn zuanti'ng. Spiciila: Megasclera long, slender tylostyli 0-22 — vo^""" ; vn'cro- 

 sclera trichoform toxa O'oS^ — 0-114""", sigmata of tivo sizes, o-02^—o-028"""- and 0-014""". 



Of this species we have a rather whole specimen and two smaller fragments. The whole 

 specimen is all but leaf-shaped, but with irregular smaller folds, and irregularly arcuate, so that one 

 side is somewhat concave. The outline of the specimen is about triangular; one edge has been at- 

 tached, while the two free edges are somewhat irregularly lobed and bent towards the concave side. 

 The height of the specimen is somewhat more than 50'""', and the thickness that is somewhat varying, 

 reaches to 10™™. The colour (in spirit) is light grayish. As in the preceding species the dermal jiieiit- 

 brane is supported by projecting, penicillate bundles of spicules, and consequently the surface is finely 

 shaggy. As the surface is damaged in most places, I can say nothing definite with regard to the 

 distribution of osciila and pores-, the pores seem to be found on both sides, but the specimen shows 

 no oscula. 



The skeleton is somewhat more richly provided with fibres than in the preceding species; it 

 consists of fibres chiefly running upward and bending towards the surface, so that they never grow 

 long; between the fibres needles are found scattered in all directions. The ends of the fibres spread 

 in a penicillate way, and pierce the dermal membrane which they support, as in the preceding species. 



Top sent says I.e., i8g6, p. 283: ; membrane spiculeuse reticulee , but the dermal membrane 



itself has no spicules (with the exception of microsclera), it is only supported by the above mentioned 

 bundles of spicules. Often these bundles are not situated vertically on the surface, but, as a conse- 

 quence of the direction of the fibres, they are directed upward towards the upper end of the sponge, 

 so that, when the dermal membrane is viewed from abo\e, fan-shaped, somewhat decumbent bundles 

 are seeu. No spongin is oVjserved in the skeleton. 



Spicttla: a. Megasclera ; these are long, slender tylostyli, almost always a little curved, especially 

 towards the head end. Generally the head is distinctly marked and rather round; the opposite end 

 tapers to a rather long and fine point. The length of the needles is much varying, the most common 

 length of the longest (fully developed) ones is between 0-83 -o-g'"™, but the length may increase to 1-05""". 

 By even transitions the size goes down to o"22"™, which is the smallest measured size. The thickness 

 of the large needles varies from 0-014 — o'Oii'"", while in the smallest ones it goes down to o-oo5'"""'. 

 Thus the needles are a little finer than in the preceding species; they are almost not fiisiform at all, 

 as the)- do not at all taper, or only taper to a slight degree, towards the head. b. Microsclera : 

 I. Toxa; these are very fine, trichoform, and have a flat curve in the middle, and a similar one a little 

 from each end; all three curves are very flat, and Schmidt tlierefore mentions these bows as feine 

 umspitzige Nadeln and \"osmaer as ac-. Otherwise the curve is sometimes a little irregular. The 

 length is between 0-085 — 0-114""", ^'^^^ the thickness in the middle is ca. o-ooi'"™. These bows are ex- 

 ceedingly abundant everywhere in the sponge, and are also found in the dermal membrane. 2. Sig- 

 mata; these occur in two different sizes; the ends of the largest are most frequently curved with a 

 more or less sharp bend, they are plane, or more or less contort iip to a quarter of a turn; their length 

 is rather constant 0-025 — 0-028°"", and the thickness is ca. 0-002'"'". The small sigmata are always some- 

 what contort, their length is 0-014'""', and the thickness' ca. o-ooi'""'. As the toxa, both kinds of sigmata 

 are found throughout the sponge, but not in so large nmnbers. 



