72 



As to the interior structure form and arrangement of the spicula, I can refer entirely 

 to Professor Loven's masterly treatise; as in these respects both species are very similar. I 

 shall only notice a few points which possibly might indicate a specific ditference: 



The spicula of the stem do not exhibit in any of my specimens an evident spiral 

 arrangement, but only lie (see fig. 40) longitudinally sometimes rather irregularly, so that one 

 has its point turned a little more to one side, and another more towards the other side. 

 Their form and length are moreover (fig. 42. a) almost exactly as in the H. boreale. Only 

 it seems to rtie that the medial enlargement in the present species is less sharply marked; 

 often it is (see fig. 43) so slight that it cannot be discovered without attentively tracing the 

 successive increase of the spiculum from both extremities. In some spicula there may be 

 remarked (ibid) a very clearly defined interior outline, in some (a) situated nearer to the 

 axial canal, in others (b) nearer to the exterior surface, and which appears to indicate 2 dif- 

 ferent strata; in most of them however the substance of the spiculum exhibited everywhere 

 complete homogeneity. 



In a longitudinal central section of the head, it appears (fig. 38) that the spicula of 

 the stem do not as in the H. boreale run conically into the interior of the club, but spread 

 themselves out fan-like in close diverging fascicles, whence again the secondary small fascicles 

 which support the parenchym radiate to the sides and upwards. On making the longitudinal 

 section through the fistular osculum, it will be seen that the latter forms a very large and 

 wide cavity, which reaches deep into the body of the sponge and here communicates with 

 other smaller cavities. The dermal part of the body of the sponge forms (see fig. 36) as it 

 were a sort of cortical layer, which however is not sharply distinguished from the interior 

 parenchym, and owes its solidity principally to the extremely numerous minute fusiform spi- 

 cula (fig. 42, f) packed together without order, which are also characteristic of the skin of 

 the stem (see fig. 40). From this dermal stratum proceed again (see fig. 39), at right angles 

 with the exterior surface of the sponge, the numerous fine terminally curved spicula (fig. 45) 

 which produce, in the perfect specimens, the very conspicuous silky exterior down that sur- 

 rounds the whole head. 



As to the exterior surface of the head, it appears under the microscope rather regu- 

 larly punctated: and this is especially plain in younger specimens. Each of the points seems 

 to be a fine pore leading into the substance of the sponge. In older specimens this fine 

 porous structure is less evident, chiefly on account of the various extraneous particles always 

 lodged between the projecting spicula, such as ooze, fine sand &c. which are not easily removed. 



I have only met with the present sponge in the great depths at Lofoten. It occurs 

 there occasionally at the fishing-stations Skraaven and Guldbrandsoerne in 120—300 fathoms 

 water on soft clay bottom. 



It has however in all probability a far wider distribution, namely both in the great 

 depths of the Atlantic Ocean and in the Arctic Ocean around Greenland, presuming that the 

 specimens sent to me by Professor Loven for comparison should really turn out, on more 



