PORIFERA. III. 



Locality: East of the Faroe Islands, depth 250 fathoms (Ad. Jensen, the cruise of "M. 

 Sars" 1902). 



13. H. stylata n. sp. 

 PI. Ill, Fig. 2, PI. VI, Fig. 9. 



Incrusting, of a thickness up to 2"""; surface smooth, with some small, conical papilla, bearing 

 oscula (and pores), and with a dense skeleton of dermal spicules in the wall. The dermal skeleton 

 strongly developed, the main skeleton weak. Spictila: megasclera; the skeletal spicules acanthostyli with 

 a small, or nearly no head, divided into two groups: large, only spined bclorv, and with the apex short 

 pointed, <?-jj o-6j"""; small, entirely spined, longer pointed, o-fj criy8 mm ; the dermal spicules long 

 strongyla o-jj 0-52 ""*/ microsclera chelce arcuatce 0-038 o' 



This species grows exclusively on loose bottom material as gravel, sand and the like; it may 

 then sometimes grow all round the material and quite imbed it, so that the substratum in this case 

 comes to lie in the interior of the sponge; this manner of growing recalls to some degree that of 

 Hainacantha implicans described in the first part of this work. The thickness of the incrustation 

 varies a good deal on account of the manner of growing, from 0-5 to about 2 mra ; moreover parts of 

 the sponge-tissue may reach in between the particles of the substratum. The specimens in hand form, 

 together with their more or less imbedded substratum, roundish or elongate bodies of a greatest length 

 of 14 mm and a thickness of 4-5""". The colour (in spirit) is whitish or yellowish grey. The sitrface 

 bears some conical papillae, which are generally more or less depressed; they may reach a length of 

 2 mm q^e sur f ace j s otherwise smooth or at all events only slightly hispid from projecting dermal 

 spicules. The dermal membrane is somewhat solid and not specially thin; it is densely filled with 

 chelse and rests on the skeleton below, but it has no proper skeleton. Oscula and pores: The above- 

 mentioned papillae bear the oscula, and I think also the pores; I have not observed pores, but there 

 seems to be some difference between the papillae, some being higher and with a distinct opening, 

 others being lower, and, as it were, closed at the apex; the latter perhaps are pore-bearing, the case 

 being as in the following species, H. verrucosa. 



The skeleton is on account of the mode of growth of the sponge, irregular, especially in 

 the deeper parts. The dermal skeleton: the skeleton formed of the dermal spicules is by far the most 

 predominant, the other skeleton being only weakly developed. The dermal spicules form bundles or 

 fibres stretching from the substratum and occupying nearly all the thickness of the sponge; they are 

 somewhat irregularly arranged, but at the surface they form distinct fibres, running somewhat hori- 

 zontally under the dermal membrane, but reaching it with the ends which have the spicules spread in 

 a penicillate way and bear the membrane. Fibres from the skeleton stretch up in the wall of the 

 papillee and form here a layer of parallel and densely arranged spicules. The dermal membrane is 

 moreover filled with chelse. In the parts of the sponge found between the particles of the sub- 

 stratum, dermal spicules are also seen. The main skeleton is as said rather feeble in proportion to the 

 whole skeleton; it is formed in the ordinary way and consists of acanthostyli with the heads inserted 

 on the substratum, but the acanthostyli are rather scattered ; they are turned in very different directions, 

 and they are found in greatest numbers in the parts of the sponge which are distributed between the 



The Infrnlf-Kxpi'flilinn. VI. 3. 8 



