70 



14, Hyalonema longissimum, M, Sars. 



n. sp. 

 (PI. VI. fig. 3545). 



Among the deep-sea sponges, which I have occasionally taken up in the dredge at 

 Lofoten together with other marine animals, I had already during my first stay there (in 

 1864) noticed one form distinguished hy its peculiar appearance. I therefore kept very care- 

 fully all the specimens I could obtain, in order to examine them afterwards. My Father 

 thought at first that we had before us a very anomalous new genus, which he in his notices 

 called preliminarily Chsetoropalium (Bristle-club). A short time afterwards Professor Loven's 

 interesting and important treatise on the Hyalonema boreale came out, in which paper the 

 author describes a very similar form, shewing its near relationship to the problematic ,,glas 

 roop Spongia" (Hyalonema), long ago well known from the Japan Sea, and completely cor- 

 recting the numerous misconceptions of the nature of this remarkable sponge. That the form 

 from Lofoten belongs to the same genus as Loven's species, is sure enough; nay it stands 



/ 



so near to it, that I have even been in great doubt as to the validity of our form as a distinct 

 species; and the more so because its dissimilarity seemed chiefly referable to the exterior 

 shape, which in sponges is known to be usually very variable in the several individuals. It 

 seems however that in some cases, even the exterior form of sponges may exist with great 

 constancy within certain limits; and to this category the genus Hyalonema seems precisely 

 to belong, as well as the 2 sponges mentioned in the foregoing lines. I have had occasion 

 to examine a great many specimens of the Lofoten Hyalonema, and have found in them all 

 a remarkable agreement in this respect; and I have also had the opportunity, through the 

 kindness of Professor Loven, of comparing them with other specimens, probably of the same 

 species, from widely different localities, namely from the Atlantic Ocean, and from the sea 

 near Greenland; and also in these have found the same differences from the H. boreale Loven 

 as the Lofoten specimens exhibit. On the other hand there was among the Greenland Hya- 

 lonema, a magnificent specimen which immediately shewed a very different habitus, and in 

 this respect very closely corresponded with the specimens described by Loven as H. boreale 

 which I have also had sent to me for comparison. As there does not therefore appear to be 

 any evident transition between these 2 northern Hyalonemes, I cannot do otherwise than 

 consider the form here noticed as a proper species, although very nearly allied to the H. 

 boreale ; and I note it here under the specific name preliminarily applied to it by my Father. 

 The length or the height of my largest specimens is 75 Mm. that is considerably 

 greater than in those described by Loven as H. boreale. But the whole form (see fig. 35. & 

 36) is far more slender and delicate; and it is specially the very different proportion between 

 the body or head of the sponge and the stem, that immediately strikes the eye and has also 

 given rise to the specific appellation. While in the H. boreale, the proportion of length be- 



