9 2 



PORIFERA. II. 



dermal membrane in the intervals between the branchlets 1 ); they were measured to a size of at most 

 Q.j.nm. t he largest ones seemed especially to occur in the parts of the skin that cover the upward turned 

 parts of the coalesced bases of the branchlets. Oscula have not been seen, but the larger of the men- 

 tioned pores may possibly be excurrent openings. 



The skeleton is constructed as in the preceding species; it consists in the stem and branches of 

 rather strong, polyspicular axes. The fibres of the branchlets are in fhe common way inserted in the 

 axes, and continue to the middle; they grow thinner and have fewer spicules outward, and they end, 

 when the branchlet is long and thin, with a few spicules or a single one. In the layer of tissue coating 

 the axis only a few, scattered spicules are found partly lying in the longitudinal direction, by which 

 spicules the dermal membrane is supported. In the axis the spicules are cemented by a distinct mass 



of spongin. 



Spicula: a. Megasclera are straight, or quite slightly, sometimes a little 

 irregularly curved styli; they are markedly fusiform, tapering somewhat, not 

 only towards the point, but also towards the rounded end. The point itself 

 is short and bounded by straight lines; it may be of somewhat varying length, 

 and in a few cases it is rounded. There is no difference between the styli of 

 the branchlets and those of the axes, only may the latter as a whole be a 

 trifle thicker, that is to say: some of them may be a little thicker, and there 

 are between them scarcely so thin styli as outside the axes. Their length is 

 from ca. 0-50— o-68 mm , and the thickness varies from 0-014— o-026 mm . Finer to 

 quite fine developmental forms occur in small numbers, b. Microsclera are 

 only of one form, anisancorse unguiferae; they are typical Cladorhiza- 

 ancorse of the common form with a regularly curved shaft and a narrow ala 

 on either side of the shaft at the upper end. They are, however, peculiar by 

 their number of teeth. In the large end the number of teeth is not constant; 

 most frequently the number is seven, not rarely, however, eight; in a few 

 cases it was six, in some others nine. The teeth are close-set and narrow. 

 The small end, on the other hand, has only five very small teeth. With regard 

 to both ends it is impossible to decide the number of teeth, unless the ancorse 

 The length of the ancorse is 0-022— o-024 mm , and the thickness of the shaft is 

 ca. o-oo2 mm . Developmental forms of the ancorse occurred in different stages. The ancorse occur in the 

 tissue and in the skin; as usual they are especially copious in the branchlets. 



Embryos. Embryos were found scattered in the sponge; they are roundish or oval, and averagely 

 of a diameter of ca. o-24 ,r "". They occur both in the stem and branches in the tissue outside the axis. They 

 were often seen at the base of the branchlets or even a little way out in the branchlets (Woodcut fig. 4). 

 If the larger of the pores mentioned before act as excurrent openings, it may easily be understood that 

 the embryos are found near them 2 ). The spiculation of the embryos is very interesting. They were either 



') They -were only seen in dried preparations. 



-1 When the embryos are found in the lower part of the branchlets themselves, it is seen that this part is hollow, 

 and the spicules of its fibre surround the embryos on all sides; farther out the spicules unite and form a fibre in the common 

 way. According to this the fact is not precluded that the embryos leave the sponge through the branchlets, and by this 



Fig. 4. C/adorhiza iuiqui- 



dentata u. sp. 



One of the branchlets with 



three embryos. X 20. 



are seen from the ends. 



