X c 2 PORIFERA. II. 



spicules smooth styli vjz—o-jo""". the dermal spicules strongyla or subtylota, most frequently with sliglit 

 spines at the ends, 0-226 — oj-'""": microsclera of one form, ancorce spatulifercr with five to seven teeth 

 0-071 — 0-097""". 



Of this species we have no great material either, only three specimens; two of them are entire- 

 ones; they are cushion-shaped and are attached with a broad base. One of these specimens, however, 

 is torn off, the other is attached to a calcareous alga. One specimen has an extent of 2o mm , and a 

 thickness of 9 mm , the other is a trifle smaller. The third specimen is the largest one; it is a much 

 damaged fragment and consists chiefly of the part that has been nearest the underlayer; it has an 

 extent of 25 mm , its form would also indicate that the whole sponge has been cushion-shaped. Also 

 this specimen is torn off from the underlayer, but both the torn off specimens show on their basal 

 surfaces pebbles and remnants of Bryozoa. The colour (in spirit) is brown. The consistency is rather 

 firm. The surface seems in undamaged places to be slightly shaggy. The dermal membrane is a very 

 thin film. Pores are found in the membrane, in places very close; they vary in size from quite fine 

 apertures to a diameter of ca. 0-2 i mm . Oscnla were not seen. 



The skeleton. The dermal skeleton, as far as I have been able to decide from the slight material, 

 consists of bundles of dermal spicules spread in a more or less peuicillate way; they project from the 

 skeleton below and are erect or more or less recumbent, and spicules are also seen in small numbers 

 lying horizontally in the membrane. In places the dermal skeleton seems to be less developed, and 

 here the fibres of the main skeleton seem to project, but this feature is perhaps due to damaging or 

 contraction. The main skeleton is a rather dense, but irregular reticulation of polyspicular fibres. Most 

 markedly occur fibres that have a tolerably distinct course towards the surface, and these fibres are 

 the thickest ones with many spicules alongside, but they have no regular course. Between them short 

 fibres and spicula bundles are found placed quite irregularly, so that a network is formed, irregular in 

 most places, and in it, moreover, many single spicules are found. A distinct mass of spongin is found 

 in the fibres, and in the nodes it becomes rather copious. 



Spicula: a. Megasclcra. 1. The skeletal spicules are smooth styli somewhat curved, most 

 frequently nearest to the head-end; sometimes they are a little irregularly curved. The point is rather 

 short, at most middle long; it may, otherwise, be somewhat varying, sometimes the style tapers evenly 

 and the outermost point is short, sometimes, on the other hand, the point may be of a rather consider- 

 able length, and in both cases it may be bounded by straight lines; in other cases the shorter or 

 longer point may be distinctly marked off. The length of the styli is 032— o-50 mm , and the thickness 

 is ca. 0-009 — o-oi9 mm . Length and thickness are often in no absolute proportion to each other, long, 

 but rather thin styli being especially often seen. Developmental forms occur in small numbers, they 

 are not rugged. 2. The dermal spicule.s vary between strongyla and subtylota. They are cylindric 

 and straight or slightly curved. The form of the ends is somewhat varying; sometimes they are 

 simply rounded or bluntly pointed and not swollen or only slightly so; they may be smooth, but they 

 have most frequently a few fine spines. Frequently, however, they are somewhat swollen, from almost 

 imperceptibly to very distinctly so, and with broadly rounded or almost cut off ends, where they have 

 more or less distinct spines; frequently the swelling is also slightly ribbed. Generally one end is 



