PORIFERA. II. 



*55 



The two specimens in hand of this species have an erect, lobed-branched form. Below they 

 are attached to shells of arenose Foraminifera. The few stubby and irregular lobes or branches issue 

 from about the upper half. The height is T,2 mm . The consistency is very soft and loose. The colour 

 (in spirit) is a dirty grayish yellow. The surface, in the present state of the sponge, is shaggy from 

 projecting spicules, but this seems partly to be owing to damaging; in the undamaged sponge I sup- 

 pose it to be finely shaggy. The dermal membrane is a transparent and very thin film, but it is 

 wanting to a great extent. Pores are found in the dermal membrane in the common way; they were 

 seen from quite small ones to a diameter of o-22' nm . Oscula were not observed, which was perhaps due 

 to the loose consistency and collapsed state of the sponge; as far as I was able to see, some large 

 canals were running longitudinally through the branches and lobes, which canals probably run to the 

 top, where the oscula should accordingly be found. 



The skeleton. The dermal skeleton is formed by dermal spicules supporting the membrane. 

 When a piece of the dermal membrane is seen from above, the spicules are seen to lie horizontally 

 in it, partly scattered singly, partly in bundles here and there, but on account of the state of the 

 material, I have not been able to observe the relation between the dermal skeleton and the main 

 skeleton. I suppose that in the undamaged sponge more or less projecting bundles of dermal spicules 

 are found. The main skeleton is a somewhat diffuse and irregular reticulation. Long polyspicular 

 fibres are found, especially in the branches; they run longitudinally through the branches in a tolerably 

 regular way, but are loose and not very conspicuous. Transverse fibres are not found between them, 

 but only quite irregularly placed spicules, almost all of which are placed singly. Regular meshes, 

 therefore, are not formed, and the whole skeletal net gives a rather irregidar picture. The ends of 

 the fibres bend towards the surface, or they give off short branches passing to the surface. Spongin 

 is found in the nodes of the skeleton, but only to a very slight amount. 



Spicula: a. Megasclera. i. The skeletal spicules are acanthostyli ; they have often a small 

 head-swelling, so as to approach subtylostyli. They are evenly curved, often a little irregularly. They 

 are evenly and middle long or rather long pointed, but the outermost point itself is most frequently 

 short pointed. The spinulation may be somewhat varying, but is most frequently rather dense, and 

 the spines are fine; they continue to the very point. The length is rather constant, from 031 — o^ci™" 1 , 

 and the thickness is ca. o - oo8 — o - oi2 mm . Very few developmental forms were seen, the finest ones were 

 already somewhat spined. 2. The dermal spicules are tylota; they are straight and have at either 

 end a longish, rather slight swelling. Their size is rather constant, the length 0-25 — o-29 mm and the 

 thickness about OTX)5 mra . The two ends of the tylota are not quite equal, one end having a more 

 distinct and more marked swelling than the other; this is owing to the fact that the shaft is not of 

 equal thickness throughout the length, but tapers somewhat towards one end, and so the swelling of 

 this end becomes more marked; this again is connected with the fact that the tylota are secondarily 

 diactinal. b. Microsclera ; these are of only one form, chelae arcuatae. The chelae have a curved 

 shaft, the curve of which is strongest in the middle, while the ends, on the other hand, are a little 

 recurved. The tooth is elliptical and rather narrow, and of the same length as the alse; the lower 

 edge of the alse is rather much indented, so that, when seen from the side, they have a somewhat 

 tooth-like form. When the chela is seen from the side in a certain position, we shall often get a quite 



