8 PORIEERA. III. 



thickness is somewhat different, from 2 to 4""" in proportion to the size of the specimen. The colour is 

 (in spirit) yellowish white. The consistency is hard and firm, the dermal rind forming a very firm 

 layer, the inner body on the contrary is soft; in most specimens the inner body has therefore con- 

 tracted strongly under the influence of the alcohol and lies like a clump in one side of the firm capsule 

 formed of the dermal layer. By exsiccation the tissue of the inner body contracts strongly, becomes 

 hard and of a yellow colour, so that it resembles wax, just as is mentioned with regard to the 

 tissue of the inner body in Oceanapia robusta (The Ingolf-Expedition VI, i, Porifera, part I, 79). The 

 surface is smooth, only showing such a slight roughness as may be caused by the spicules imbedded 

 in the dermal layer and parallel to the surface. The sponge has outermost a very solid dermal layer 

 of a thickness of about o-25 mm ; in places it may become thicker, up to i mm ; it surrounds the inner 

 body like a mail and is very easily loosened from it, and contains close-lying spicules in several 

 layers. Pores and oscula: Carter says: "Pores and vents not distinctly seen, but probably situated at 

 the extremities of the tubuli respectively". This is also the case, but I too cannot solve the question 

 with full certainty, because most of the tubular appendages are broken off. The oscula are certainly 

 situated at the end of some of the fistulae; these latter are tubular, hollow and somewhat thin-walled; 

 a couple of them give the impression of being undamaged, and these terminate with a simple opening 

 which in consequence should be the osculum; a couple of the fistulae terminate with a formation 

 quite as described by Carter, it is with a conical spout, placed at the end of the fistula; whether this 

 is possibly the normal, closed osculum I do not venture to decide. Of poriferous fistulse there is in the 

 material only one present, a loose tube which is broken off and has a length of 2O mm ; this tube shows, 

 that the fistulse become more thin-walled outwards, and that the skeleton in the wall becomes more 

 scattered. The end of the fistula is rounded and forms a slightly swollen knob of a length of about 

 2-5 nim ; in this knob the skeleton of the wall is transformed and passes into the formation of a reti- 

 culation, in the meshes of which the pores are situated (PI. I, fig. n); the pores are oval or circular, 

 of a diameter of 0-047 O'i7 mm - In the dermal layer on the other parts of the body no pores are 

 found. As mentioned the inner body is inclined to get strongly contracted in alcohol and become 

 hard and brittle, and there is then a large hollow space inside the dermal layer. But in single cases 

 the inner body has on the contrary preserved its original shape and consistency; it then quite fills 

 out the cavity formed by the dermal layer. When a section is made of such a well preserved speci- 

 men, the canal system is shown; some large canals are seen terminating in some of the tubes, and 

 thus shown to be excurrent canals (PI. I, fig. 8); besides, a multitude of smaller canals are seen. The 

 inner body lies quite loose in the cavity within the dermal rind, and it seems only to be attached at 

 the points where the fistulae issue; thus there are extended spaces below the dermal layer. The lumen 

 of the fistulae is not directly continued into the canals of the inner body, as there is a diaphragm 

 present at the origin of the fistulae; this diaphragm has in some cases a circular opening in the 

 centre, but it seemed in other cases to be quite closed. When the dermal rind is removed, the surface 

 of the inner body is shown; this surface is then quite undamaged, and it has the netted appearance 

 which is so often seen on the surface of species of Rcniera (PI. I, fig. 9); on examining a specimen 

 which wanted the dermal layer, one might, therefore, think that it must be an entire and un- 

 damaged sponge. The netted appearance of the surface is due to the same cause as in the species of 



