jg POR1FERA. II. 



from the opening itself, which is thus surrounded by a narrower or broader brim (probably changing 

 according to the degree in which oscula are shut) of the membrane without styli. On the other hand, 

 microsclera, especially the smaller form of ehelse, are found here in large numbers. Pores are only 

 found on one side of the sponge where the spicules are arranged in a net-like wav; they are round 

 or oval, and have been measured to a size of 0^03 — o , 238 mm . As the pores are thus only found on one 

 side it is possible that oscula are only found on the other, and this, perhaps, is again dependent on 

 the form of the sponge; the fact cannot, however, be decided from the fragments in hand. 



The skeleton consists of polyspicular fibres branching up through the sponge from the lower 

 part and here and there anastomosing; in the upper part of the sponge they run as more or less 

 parallel fibres. Here they all bend towards one side of the sponge, and run perpendicularly towards 

 the surface. The consequence of this course of the fibres is that they are more or less parallel to 

 the other side of the sponge. The side towards which the fibres bend, is the poreless one; thev are 

 here connected with the close-lying spicules of the dermal membrane, and support the membrane, but 

 do not pierce it. The dermal membrane on the other side, which, as mentioned, is provided with 

 pores, and the spicules of which form a reticulation, rests on the fibres running below it. The fibres are 

 polyspicular, and consist of rather many spicules beside each other; they are of an average thickness 

 of 0-09 — o - i2 mm . Between the fibres a quite irregular network is found, partly of fibres with few spi- 

 cules, but chiefly of single spicules. In the lower parts of the sponge the longitudinal fibres are more 

 close-standing than farther up. The spicules of the fibres are connected by a clear, not copious mass 

 of spongin apparently, however, wrapping the whole fibre; it is especially distinct in the nodes. 



Spiatlit: a. Megasclera are styli; the}' are slightly curved in various ways, and sometimes 

 somewhat irregularly; they may also be almost straight. They taper evenly, but most frequently not 

 much towards the point, and the point itself is therefore most frequently more or less suddenly pointed 

 and may be longer or shorter, clown to quite short; it is frequently more or less distinctly marked off, 

 and the marked off point may also be longer or shorter. The needles are often a little thinner below 

 the rounded end than at the end itself, but they cannot, however, be designated as subtylostyli. The 

 length is between 0-54 and o-68 mm , and the thickness is o-oio— croi4 mm ; the thickest ones are generally 

 uot the longest Finer, down to quite fine developmental forms are found, but only in small numbers; 

 they are only a little shorter than the fullgrown ones, the finest ones have a length of o-47 mm . The 

 developmental forms are all long tapering, b. Microsclera ; of these are found two forms of isochelse, 

 smaller isochelse palmatse and larger isochelse arcuatae, further sigmata and forcipes. 1. The small 

 palmate isochelse may be somewhat varying in form, the middle part of the shaft between the end 

 parts being straight, or more or less curved ; this part is a little more than one third of the length 

 of the chela. When the middle part is curved the whole shaft forms an even curve; when it is straight, 

 the end parts, from which the lateral alse go off, form obtuse angles with the middle part; the tooth 

 being directed somewhat forward the angle between the tooth and the shaft becomes rather large. 

 The tooth is of about the same length as the alse, but it is considerably narrower than these taken 

 together, and is ovate; the lateral edges of the alae are refolded through the whole length, so that 

 the folded part is seen, when the chela is seen from the front. These chelse are very small, their length 

 is between cron — croi8 mm , and their greatest breadth is ooo7 mm . 2. The arcuate isochelse have 



