, PORIFERA. II. 



more shaggv than in the preceding species. The dermal membrane is thin and has no particular 

 skeleton, but is supported by the ends of the fibres projecting through it, and by the transverse 

 spicules connecting the fibres. Pores and oscula. As mentioned above we find in this sponge as in 

 the preceding one furrows in the surface that may present a very varying arrangement. These fur- 

 rows are also here pore areas, the dermal membrane being stretched over them and provided with 

 pores quite as in the preceding species. The pores are placed very close, and most frequently more or 

 less arranged in transverse series separated by thicker principal strings. Also here a fine, muscle-like 

 longitudinal striation is found in the strings of the tissue between the pores, which striation was 

 seen still more distinctly than in the preceding species. The pores are round or oval, and in the 

 examined pore area they had an average diameter of about 0-015— o-o2 m,n . The pore furrows in the 

 specimens in hand are smaller and are present in smaller numbers than in the preceding species; in 

 one of the specimens they are all quite closed, and then they appear as quite narrow keels arranged 

 in a somewhat netlike manner. Pores seem also to be found outside the pore furrows; but it is diffi- 

 cult to decide this fact by material which is not fresh or especially well preserved. Ridley and 

 Dendy state it to be found in E. murrayi. Oscula are small, more or less steep cones of a height of 

 2 — 3 ,nm . The oscular aperture is found in the end of these cones. The wall of the cones is provided 

 with a very dense speculation of spicules parallel to the longitudinal axis of the cone, and their ends 

 project round the aperture. In the larger specimens oscula are found in rather large numbers and are- 

 restricted to the upper half of the sponge. 



The skeleton is of a dendritic type, and is constructed as in the preceding species. It consists 

 of fibres branching from the base up through the sponge and anastomosing. Also here the single 

 fibres are closely united into thicker ones that are apparently single ones, and these thicker fibres are 

 often not cylindrical. The single fibres have been measured to a thickness of at most o-65 mm . Towards 

 the surface the skeleton sends forth finer branches running parallelly, and supporting and piercing the 

 dermal membrane; between these fibres some transverse spicules are found. The ends of the fibres 

 which appear as bundles of spicules, are in this species formed of spicules of the same kind as the 

 other spicules of the fibres, so that no specially formed dermal spicules are found. The transverse spi- 

 cules found between the fibres that are parallel and run towards the surface, are also in this species 

 of a form somewhat different from the form of those forming the fibres, being shorter, thicker, and 

 curved. A slight amount of spongiu unites the spicules of the fibres, but is only little conspicuous. 



Spiatla: The spiculation of this species is upon the whole like that of the preceding one. 

 a. Mcgasclera are styli, or may have a slight tendency towards subtylostyli. Most of them are straight, 

 but some are slightly curved ; they are fusiform, tapering towards both ends, which holds good especi- 

 ally with regard to the shorter and thicker ones. The upper end is rounded and sometimes quite 

 slightly swollen ; the handle-like form of this end mentioned under the preceding species, is also some- 

 times found in the present one, and also here developed to very different degrees. The other end of 

 the needles runs into a point, which may, especially in different individuals, be very varying in length, 

 from being quite rounded to a long, fine point. The length of the needles is rather varying, as well 

 in one individual as in different individuals. As mentioned the transverse spicules between the fibres 

 running towards the surface are shorter and thicker than the other spicules, a distinct limit, however, 



