274 



ERYLUS SOLLASII. 



irregular lobose mass with small gyriform ridges on parts of its surface and 

 measures 78 by 62 by 40 mm. On or near the summits of some of the lobes 

 oscules are observed. The largest are oval and measure 4 by 2 mm. The other 

 parts of the surface are occupied by groups of small pores. 



In regard to their colour the (spirit) specimens differ to a considerable 

 extent. The two specimens from Station 3848 (race I, form C) are for the most 

 part yellowish white, only some of the protruding parts having a purplish brown 

 tinge. The specimen from Station 4062 (race I, form D) is dirty light brownish 

 gray. The lower, basal portion of the partly dark, partly light-coloured speci- 

 men from Station 3847 (race I, form A) is light gray, the upper portion dark 

 chestnut-brown. In the entirely dark specimen from the same Station (race I, 

 form B), the surface is dark chestnut-brown throughout. The specimen from 

 Station 3849 (race II) is dirty brownish purple, some parts of its surface being 

 considerably darker than others. The specimen from Station 4055 (race III) 

 is rather dark purple-brown. 



The superficial part of the body is differentiated to form a cortex (Plate l, 

 fig. la). This is 100-250 // thick and composed of an outer, middle, and inner 

 layer. The outer, dermal layer is generally quite insignificant and on parts of 

 the surface of most of the specimens absent altogether, probably rubbed off. 

 In those parts of the cortex of race II where it is most highly developed, it 

 attains a tliickness of 30 ft. This layer is rich in microrhabds, but contains no 

 fibres and no aspidasters. The middle layer is from 83 f^ (in parts of the cortex 

 of race II) to 210 /j. (in parts of the cortex of race III) thick and occupied by 

 dense masses of aspidasters. The inner layer is often insignificant and hardly 

 to be made out in the sections. In race I, form C, it attains in places a thick- 

 ness of 20-30 fi. It is composed of paratangential fibres and contains a few 

 granular cells and groups of granules. 



Granular cells, oval to spherical in shape and 12-18 fi long, are abundant 

 in most of the specimens. These cells are most numerous just below the cor- 

 tex and here often quite densely packed (Plate 1, fig. 3). They also occur 

 scattered in the interior of the choanosome. These cells are filled with granules 

 of fairly equal size. In the granular cells of pale parts of the sponge, particu- 

 larly in the region overgrown with symbionts, the granules are colourless. In the 

 subcortical and cortical granular cells of the dark and exposed parts the granules 

 are brown. Both the colourless and the brown granules stain deeply with 

 aniline-blue. As mentioned above a few granular cells and groups of granules 

 also occur in the inner layer of the cortex. These groups of granules are 



