58 



porifb;ra. I. 



has only one fistula arising from one end, and with a length of ii""" and a thickness of ca. 4'""'. The 

 largest one of the roundish specimens has a greatest extent of 24"""; the smallest specimen is scarcely 

 gmm long. With the exception of the first mentioned specimen, the fistuke have been broken off in 

 all the others; b)- far the greatest number have had onl\- one fistula, a single specimen has had 

 two, and one of the smaller specimens, as far as ma>- be judged, has had three fistulse. Some of 

 the specimens are highly incrusted with sponge-spicules, sand, or fragments of shells. On account of 

 the external bark the sponge is rather hard, but in the interior soft and loose. The colour (in spirit) 

 is white or yellowish white. The surface is not quite smooth to the touch, projecting spicules being 

 found sparingly. Externalh' the sponge is provided with a part marked off as a dcniial !<ivn\ which 

 is, however, most frequenth" rather thin, ca. ot'"™; this lax'er is provided with spicules h'ing in every 

 direction; hx far the greatest niuuber are parallel to the surface, but some are placed obliquely or 

 verticalh' to the surface, so that the\' rise over it; these last-inenticjned sjiicules mav in different places 

 of the surface of the sponge be present in different numbers. A thin, separable dermal membrane is 

 not found. The pores are found in the skin, but I have only seen them in rather small numbers; 

 their .sizes are about 0-02 — o-03""". Oscula : As the fistuke are broken off in almost all the specimens, 

 I have not been able to decide the features of this species with regard to oscula and the structure of 

 the fistulse. The question, whether the fistulse of these sponges are open or closed at the ends, has 

 been answered in different wa\s b\' the authors, and also differently with regard to different species. 

 There is also a possibility that there ma\- be some difference in this respect in the different species; 

 but whatever may be the case with regard to this feature, there can scarcely be any doubt that the 

 canals that always go into the fistulae, are excurrent canals, and that the fistuke accordingly act as 

 oscrda. The only apparently whole fistula in the specimens of the present species, appeared to be 

 closed at the summit, Imt then it did not appear to be built normally; possibh' it may have been 

 damaged, and have been closed by its later growth. As on the other surface pores are found in the 

 walls of the fistula, but only in small numbers. In the fistida are found, at all events very frequentl}-, 

 two larger canals running alongside of each other; but besides smaller cavities are seen outside of these 

 canals, which latter I take to be subdermal cavities. In one of the smallest specimens that is provided 

 with a rather long fistula, this fistula is thin-walled in the outer end, and here it is quite occupied by 

 the two canals which are separated by a thin jiartition-wall. 



The skeleton. Besides the mentioned external part marked off as a dermal layer, highly pro- 

 vided with spicules, the other skeleton that fills up the interior of the sponge, consists of a quite 

 irregular tissue of spicides forming neither fibres nor meshes. But besides the skeleton has a parti- 

 cular, somewhat lamellar structure, being traversed by lasers of spicules of a structure quite similar 

 to that of the dermal layer, consisting of close-set spicules parallel to the direction of extent of the 

 layer. The lasers are more or less concentric, and parallel to the surface of the sponge. They appear 

 ([uite or partly to continue all round the sponge, but the\- may pass into each other, and in some 

 places they are seen to pass into the skin"). I am not able to decide, in what manner this structure of 

 the skeleton is to be interpreted, but most likely it is a phenomenon of growth. The spicules of the 



■) This structure of the .skeleton is not directly seen in a specimen in spirit when cut through; but when the spe- 

 cimen is dried it is distinctly con.spicuous, and under the microscope it is distinctly seen in sections lying iti xylol. 



