144 



PORIFERA. II. 





specimens. The localities are situated in the Davis Strait (station 32), in the Denmark Strait (stations 

 85, 89, and 98), north of Iceland, round the Faroe Islands and off the coast of Norway. The depths 

 are from 30 — 318 fathoms. 



Gcogr. distr. The species was hitherto only known from the Shetland Islands (Bowerbauk). 



4. M. brunnea Arm. Hans. 

 PL IV, Fig. 11. PL XIV, Fig. 6 a-h. 

 1885. Myxilla brunnea Armauer Hansen, The Norwegian North-Atlantic Exp. XIII, Spongiadse, 12, 

 PI. Ill, fig. 1 d, PL VI, fig. 5. 



Erect, more or less irregularly leaf-shaped, sometimes lobed or in other zuays irregular. The sur- 

 face grooved or curly, not shaggy, or only imperceptibly so. The dermal membrane a rather thin film, 

 supported by pcnicillate bandies of dermal spicules, and in some places with horizontal spicules. The 

 skeleton a somewhat irregular, chiefly polysplenia/- network with quadrangular or irregular meshes : 

 primary longitudinal fibres are found running up through the sponge and bending towards the surface. 

 Spicula : Megasclera: the skeletal spicules acanthostyli and acanthostrongyla o-2j8—o-j8""". the dermal 

 spicules lomota with two- to four-pointed ends 0-20 — o-2g"""; microsclcra two forms of ancora spatuliferce, 

 large ones 0-05 j — o-o6^""", small ones cro2/ — o-ojj""". 



This species is erect, and is more or less, but often very indistinctly leaf-shaped. It is attached 

 below ; the specimens that have not been torn off from the nnderlayer, are attached to shells, Balance 

 or stones. The most regular specimens are quite leaf-shaped, and are at the base narrowed to a quite 

 short stalk. Of this form we have one specimen, 95 mm high, 65""" broad, and ca. 5 mm thick. Then we 

 have some specimens that are more irregular, the leaf being thicker and more irregularly lobed, and the 

 form of a leaf may be quite effaced. These specimens, which appear to have been attached with a broad 

 base, are 40 — 75 mm high and of similar breadths. A few smaller specimens are more ramiform. Finally 

 we have a specimen attached to a stone, which from a lower lobed part passes above into two lobes 

 forming together an open, bilobate calyx. The consistency is little elastic and rather brittle; the thin 

 leaves are more flexible. For some of the specimens taken by the Ingolf, the colour of the fresh sponge 

 is stated to have been dark orange; in spirit all the specimens have a dark brown to almost quite black 

 colour; only very few ones are of a lighter shade. When cut through they show a lighter colour inside. 

 The surface is highly grooved or curly; for, the sponge being traversed bv a number of horizontal canals, 

 the dermal membrane forms over their mouths sunk grooves, separated by curly or sinuous ridges. The 

 surface is otherwise smooth, or finely, almost imperceptibly shaggy from projecting dermal spicules. 

 The dermal membrane is a rather thin, but tolerably solid and easily separable film, partly supported 

 by peniciliate bundles of spicules, partly provided with scattered spicules. The pores are, as usual, 

 lying in the dermal membrane, sometimes scattered, sometimes very close-set; they are round or oval, 

 but in places where they are close-lying often of an irregular form. They were measured to about 

 0-029 — 0"23 n,m . The question as to the oscnla is not easily decided. A great number of canal-mouths 

 are seen in the surface, but many of these apertures have evidently their origin from the fact that 

 the dermal membrane is damaged, either torn over the canals, or quite wanting, and it is impossible 

 in each single case to decide, whether damaging has taken place. Where, however, the membrane is 



