PORIFERA. I. 105 



1892. Haiuacautliajolnisoni \-ar. coviflanata, partiiii, specimen rhaphidibus insintctum, Topsent, Resultats 

 des Campagn. scient. du Prince de Monaco, Fasc. II, 87, PI. \H, fig. 5 b, li. 



Formed like a flat cushion, or more or less crust-shaped, provided 7vifh more or fewer, round or 

 flattened, cottical papilla'. Embodies extraneous bodies copiously, especially in the part turned toivards 

 the substratum. Outermost the sponge has a rather firm dermal layer provided zuith close-lying spicules 

 in several layers parallel to the surface^ but otherivise lying in every direction; from these layers close- 

 standing spicules project, and tlierefore the surface is shaggy. Oscula are found at the s^immits of the 

 papillce.. The skeleton consists of irregtilarly rtmning, polyspiciilar fibres and scattered spicules. Spongin 

 wanting. Spicula : Megaselera sty li 0-2'/ — o-68"""; microsclera diancistra of one form o-ig — o-22''""; rka- 

 phides in trichodragmata o-ii""". 



This species has a quite pecuhar way of growing; it grows as thinner or thicker incrustations 

 on shells of MoUusks, Bryozoa, worm-tubes, stones etc.; but generally it spreads over the body on 

 which it is growing, grows round it, and embodies it completely; sometimes the substratum has only 

 been small stones and particles of gravel, and even if it grows on a more extended substratum, it 

 always includes extraneous bodies copiously, so that, when a specimen is cut through, the lower half 

 is always found abundantly filled with foreign bodies, especially pebbles and gravel (PL V, fig. 9). These 

 particles are kept together and surrounded by sponge-tissue. Besides thus having incrusted foreign 

 bodies, the sponge moreover is most freqiiently somewhat incrusted on the outside, and on account of 

 its form folds and hollows may be formed, which, as it seems, may be quite closed by coalescings, and 

 be filled with gravel and the like. Thus these cavities belong originalh- to the surface of the sponge, 

 and bv the cutting through of a sponge, in which they are found, cavities will accordingly be found 

 filled with foreign particles, of which cavities some belong to the interior of the sponge, while others 

 belong to the surface; they may, however, be distinguished from each other by the fact that the sur- 

 face of the sponge is finely shaggy, and therefore the walls of the cavities, which do not belong to 

 the interior of the sponge, but have their origin from coalescings, are shaggy from projecting spicules. 

 The form of the sponge may otherwise be somew^hat varying according to the substratum, on w^hich 

 it is growing; when growing on large, flat shells, it forms a regular crust or cu.shion, while it is 

 oftenest more or less irregular, when growing on smaller bodies. The largest specimen in hand, 

 growing on a Pecten-sheW, has a greatest extent of ca. 47""" and a thickness of 6—7'""'. The other 

 specimens grow^ especialh- on bi\-alves and Brachiopods, and are most frequently growing on, or have 

 incrusted, several shells. The surface is set with a larger or smaller number of conical papillae, formed 

 bv the skin; the papilhe have an average length of 5—7"""; they are either round or flattened. Other- 

 wise the surface is shaggy- from projecting spicules. The sponge is very cavernous, and especially in 

 the upper part, where no extraneous bodies are embodied, large cavities are found immediately imder, 

 the skin; therefore it is of a somewhat vesicular consistency. The colour (in spirit) is grayish white 

 somewhat transparent, but often it appears to be brownish on account of sand and mud covering it. 

 Externally the sponge is provided with a rather firm dermal layer furnished with rather close-lying 

 spicules intercrossing in all directions, but parallel to the surface; they are lying in several layers, 

 and the part marked off as skin, has a thickness of ca. o-io™'". Through the spicules of the skin other 



The Ingolf-Expedition. VI, i. '4 



'"i-^, 



