IO PORIFERA. II. 



1887. Esperia villosa Fristedt, Vega-Exp. vetensk. Iakttag. IV, 451, PI. 25, figs. 33 — 39, PI. 29, fig. 19. 

 1904. Esperiopsis villosa Topsent, Resultats des Camp. Scient. dn Prince de Monaco, Fasc. XXV, 211, 

 PI. XVII, fig. 2 a— c. 



Erect, more or less irregularly leaf-shaped. The surface finely shaggy from projecting spicules ; 

 the dermal membrane thin, with no separate skeleton, resting on spicules that are spread in a peni- 

 cillate way. Oscula formed as small, conical projections, along the upper edge or a little down on the 

 surface. The skeleton consists of polyspicular fibres branching up through the sponge and anastomosing; 

 from this skeleton shorter fibres go off to the surface. Spicula : Megasclera styli or slightly -marked sub- 

 tvlostyli o-6 — o-/j'" m ; tuicrosclcra of four forms : isochchr pabnatcr of three forms, large ones of a parti- 

 cular narrow form 0-08 — o-/2""". middle ones o- 078—0-092""", small ones 0-021 — o-oji mm ; sigmata, large 

 0-045 — o-ig""". 



This species has been pretty well described by Carter with the only misconception of the 

 mutual relation of the three different chelae, which is a consequence of his wrong interpretation of 

 the growth and development of these bodies. The species seems most frequently or always to be 

 erect and more or less leaf-shaped, but is otherwise of somewhat varying form and thickness, and 

 frequently of an irregular appearance. With its base it is fastened to stones or some other underlayer, 

 and most frequently its base is widely spread. The largest specimen in hand is of a height of ca. 

 i3 c,n and a thickness of about 15 — 20 mm . The colour (in spirit) is generally gray, sometimes passing a 

 little into brownish. On account of its skeleton the sponge is rather firm, but may, however, be torn 

 easily, and all the specimens are much damaged. The surface is finely shaggy on account of the 

 projecting spicules. The dermal membrane is thin, with no skeleton, supported by spicules projecting 

 in a fanshaped way. The pores are situated in the dermal membrane between the projecting spicules; 

 sometimes they are very close-set, so that the membrane becomes a network. They are round to 

 oval, and their size is generally between 0-02 and o - i5 mm . Oscula are constructed in a peculiar way; 

 along the upper edge of the sponge, or sometimes a little down on the surface is found a number of 

 projections quite slightly conical ; they are of an average height of a few mm., and have a diameter not 

 exceeding i mm . They consist of spicules and are apparently solid, but when cut off at the base they leave 

 a hole, and are seen to be hollow in their lower part; in a few of them a little opening is also found 

 in the top. All the oscula (they are only found distinctly in the best preserved specimen) may be 

 supposed to be shut, open oscula were not seen. Further down on the sponge a few round holes are 

 seen, which I take, however, to be due to damaging 1 ). From the osculum a canal may generally be 

 traced some way down in the sponge. 



The skeleton consists of irregularly branched, polyspicular fibres, branching from the base up 

 through the sponge, and frequently anastomosing. They are thickest in the lower part of the sponge; 

 in the middle of the sponge they have an average thickness of ca. o - 35 mm ; they are polyspicular, and 

 have a great number of spicules side by side. The fibres with their anastomoses form a rather dense 

 and solid skeleton. From this skeleton close-set fibres go off to the surface generally curving some- 

 what upwards. These fibres divide on the way to the surface, and pierce the dermal membrane as 



') When Carter (I.e. 1874) says: ^Vents scattered here and there irregularly', it is presumably owing to the fact 

 that his specimen has been damaged, and the real oscula have been wanting or indistinct. 



