Miscellaneous. 237 



expedition is fulfilling the object for which it was sent out. The 

 naval and the civilian staff seem actuated by one wish to do the 

 utmost in their power, and certainly a large amount of material is 

 being accumulated. 



The experieuces of the last three months have of course been 

 somewhat trying to those of us who were not accustomed to a 

 sea-life ; but the health of the whole party has been excellent. 

 There has been so much to do that there has been little time for 

 weariness ; aud the arrangements continue to work in a pleasant 

 and satisfactory way. 



(Signed) Charles Wyville Thomson. 



MISCELLANEOUS. 



A new Order of Hydrozoa. By Geokge J. Allman, F.R.S. &c. 



On the southern shores of France, at a slight depth below the 

 surface of the sea, there may be found attached to stones small 

 patches of one of the horny sponges which will probably arrest the 

 attention of the zoologist by what will appear to him as an un. 

 usually obvious and well-defined condition of their efferent orifices 

 or oscula. 



If one of these patches be transferred to a phial of sea-water, 

 the observer will soon be astonished by seeing that from every one 

 of the apparent oscula a beautiful plume of hydroid tentacles 'will 

 have become developed, and he will naturally believe that the form 

 has at last been found which will remove all doubt as to the zoolo- 

 gical position of the sponges, and decide in favour of the hydroid 

 affinities recently assigned to them *. 



A more careful examination, however, will show that the orifices 

 on the surface have been incorrectly regarded as oscula, and that 

 the tentacles form no part of the sponge, but proceed from an 

 entirely different organism which is imbedded in its substance. 



It will be further seen that the organism with which the sponge 

 is thus associated is contained in a congeries of chitinous tubes 

 which permeate the sponge-tissue, and open on its surface in the 

 manner of genuine oscula ; and it will be still further apparent that 

 this organism, while undoubtedly a hydrozoon, and even presenting 

 quite the aspect of a hydroid trophosome, is no hydroid at all, and 

 cannot indeed be referred to any of the hitherto recognized orders 

 of the Hydrozoa, but must take its place in an entirely new and as 

 yet undefined order of this class. 



The chitinous tubes and their contents are united by a common 

 tubular plexus which lies towards the base of the sponge, and they 

 thus constitute a composite colony of zooids. The tubes, towards 

 their free extremities, where they open on the surface of the sponge, 



* See Haeckel's " Kalkschwamme." 



