n PORIFERA. II. 



between the styli of the axis and those of the branchlets and the layer of tissue, the styli of the axis 

 being only upon the whole a little longer and especially a little thicker. With regard to the length 

 styli may be found in the branchlets as long as the longest ones in the axis, but upon the whole 

 they are shorter, and styli may be found here considerably shorter than are generally found in the 

 axis; also are the styli of the branchlets almost always longer pointed. The length varies at most 

 from ca. 0-58 — roi m,n , and the thickness from ca. 0-014— o-0257 mm . With regard to the axial styli 

 the length rarely goes below 070 ,nm , and the greatest thickness attained by the styli of the branchlets 

 is ca. o-02i mm . In the branchlets long, fine styli with long points occur rather frequently, which 

 are, no doubt, developmental forms, b. Microsclera are anisancorse unguiferae with five teeth and 

 sigmata of two forms. 1. The ancorae are of the common Cladorhiza-type, and are constructed 

 quite as in the preceding species. Their length is 0-024 — o-028 mm , and the thickness of the shaft in 

 the middle o-oo28 mm or a little less. Developmental forms in different stages are rather frequent. 

 2. Sigmata of the first form are fine, of the common sigma-form; they have a somewhat curved 

 shaft and regularly round-curved ends; they are contort up to the fourth part of a turning, most fre- 

 quently, however, somewhat less. They have not the edge-like expansion occurring in the other form 

 of sigma, but are not, otherwise, quite cylindric, but seem to be somewhat compressed through their 

 whole length. Their length is 0-038— 0-048™"', and the thickness about 0-0014"™. 3. Sigmata of the 

 second form have a similar form as, and correspond to, the smaller sigmata of the two preceding 

 species; they have an almost straight shaft, and their ends are somewhat compressed, but to a far 

 smaller degree than in the preceding species. They are contort and always one fourth, or about one 

 fourth, part of a turning. Their length is 0-048— o-056 mm , most frequently nearest to the smaller size. 

 The thickness is about o-oo25 mm . The two forms of sigmata are easily distinguished; the former is 

 especially distinguished from the latter by being finer and having no expansions towards the ends, 

 by its curved shaft, and by its being generally twisted less than one fourth of a turning. It can only 

 be confounded with developmental forms of the second kind. The two forms occur in distinctly limited 

 parts of the sponge; sigmata of the first form occur in the tissue of the whole sponge, except in the 

 end-knobs; in these, on the other hand, sigmata of the second form are exclusively found, and in 

 copious numbers; but none of the sigma- forms occur in anything like the number of the ancorae, 

 which are present in great abundance throughout the tissue, especially in the dermal layer. 



Embryos. Embryos were found in most specimens of this sponge. They are lying in the tissue 

 outside the axis, often rather closely, but each in a cavity of its own, and each embryo is surrounded 

 by a membrane. They are globular or somewhat oval, and of a diameter of up to o'5 m:n . The spicu- 

 lation is different in the different stages ; some have no spicules, others only ancorae, and others again 

 have both ancorae and styli. The ancorae are smaller than in the developed sponge, most frequently 

 of a length of 0-017— o-02i mm , and also rather fine. The styli are likewise small and very fine. The 

 styli are arranged in a bundle about in the middle of the embryo, while most of the ancorai seem to 

 be chiefly placed in the circumference. None of the two forms of sigmata were seen in the embryos. 



This species is very similar and closely allied to the preceding one; in its outer form it is 

 especially distinguished from the former by the more or less marked circular arrangement of the 



