PORIKERA. I. 91 



As to the exterior, my specimens of the species agree ver>- well with the figure of Bowerbaiik. 

 The species may have a very various form which seems, however, to be connected with the age of 

 the individual. It begins as a little cushion which may be higher or lower, and which ma\, on 

 account of the ends of the fibres that project through the conical processes of the skin, to some degree 

 resemble Haliciiciuia vcrticillata Bow. We ha\'e two specimens of this form, one of which has a breadth 

 of 8""", and a height of 5™'", the other has a .similar breadth, but a height of 12"™. Both these speci- 

 mens are attached to a Sip/10. In growing it rises more from the substratum, and assumes a leaf- 

 shaped or calicular form. It is possible that in the grown state it is normallj' of a calicular form, as 

 the leaf-shaped pieces in hand are fragments; the largest specimen in m\- possession, which is, how- 

 ever, highh' damaged, has an open calicular form; it has a height of 57'"'", and the wall has a thick- 

 ness of about 10 — 15""". It has been attached by a rather small base. Bowerbank's .specinien is 

 somewhat larger having a height of about 100™". The surfacr of the sponge which is onh midamaged 

 in the smaller specimens, is characteristic h\ the fact that it rises into rather close-set, conical pro- 

 cesses pierced by the ends of the fibres. On account of the solid skeleton the consistenc\- is rather 

 firm and somewhat elastic. The colour (in spirit) is brown or grayish brown. The dermal inniibrane 

 is very thin, and is supported by the ends of the fibres; it is only provided with microsclera; first 

 rhaphides are found of two different sizes in bundles, they are scattered without any order, and in 

 some places only the long ones are found, in other places only the short ones. Next two kinds of 

 sigmata are found in the skin, of which especially the small ones are found abundant!}-; finalh' com- 

 mata are found in no small number, but on account of their smallness they are only little conspicuous 

 and difficult to observe. Osciila and porrs : I have only with certainty observed pores in the smallest 

 of my specimens where they were found in large numbers in the fields between the projecting ends 

 of the fibres, so that here the skin in several places was reduced to a sieve. Their form varied from 

 round to oval, and the size was measured to 0-05— o- 15""". As the skin was wanting in most specimens 

 I have onh- been able to examine it in a deficient way; I am, however, inclined to think that it will 

 show features similar to those mentioned under the following species. In the specimens in which the 

 skin was tolerably undamaged, a few scattered circular holes were seen of a .size of 1-5— 2-5""" (they 

 were onl)- seen in the small specimens); these openings I take to be oscula. 



The skcletnii consists of rather powerful polyspicular fibres branching upward from the base 

 of the sponge and anastomosing, so that they form a rather dense reticulation. The>- are thickest 

 below, and ma\- here reach a thickness of up to o-s™™, otherwise the average thickness is about 0-2""". 

 Branches from the fibres bend everywhere outward, and support and pierce the dermal membrane, as 

 before mentioned. The spaces between the fibres are filled by an irregular network of the finer 

 branches and anastomosings. The spicules of the fibres are cemented b\- spongin which is not, how- 

 ever, seen to coat the whole fibre. The spongin is seen especially distincth- where branches go off 



from the fibres. 



Spicnla: a. Megasclera are styli, more or less, oftenest slighth- curved, and almost alwa\s with 

 the curve nearest to the upper end; the other end runs into a long, evenh- tapering point, the outer- 

 most end of which may be more or less shortly pointed; especially in the .shorter and thicker spicules 

 the point is often short. The length is somewhat varying, from about 1-5— o-Sj™™; in this respect some 



