244 Tin. N. ANNANDALE ON FKESHWATER 



With the prevailing greens and blues of the transmitted light there remains 

 little else than intense black, contrasted with a light backgromid, to serve for 

 warning or recognition marks. 



There is a common littoral fish (Uranoscopus scaber), a member of the same 

 family as Trachinus, found in the Mediterranean Sea. Its habits, as regards 

 burying itself in the sand, appear to be closely similar to those of the Trachini 

 and it has an erectile first dorsal fin of a jet-black colour. There is a for- 

 midable spine on the operculum, and this fish, like Irachinus, is said to be 

 poisonous. It inhabits the same grounds as Trachinus, and a black or black- 

 and-white first dorsal fin appears to be as characteristic of the genus Urano- 

 scopus as it is of the genus Trachinus. It is difficult not to conclude that it 

 obtains a considerable amount of protection by possessing a conspicuous black 

 dorsal fin, and that its close resemblance to TracJiinus may be of mutual 

 service to both kinds of fish. 



On the other hand, it seems a general rule that in sand-loving round fishes, 

 whatever colour-markings may be necessary tend to become concentrated in 

 the dorsal fin, which alone is visible when the fish is buried in sand 

 (c/. Gobiidse, Centronotidee, &c.). 



Notes on some Freshwater Sponges collected in Scotland. By 

 N. Annandale, D.Sc, F.L.S., C.M.Z.S., Superintendent, Indian 

 Museum, Calcutta. 



[Read 2nd April, 1908.] 



As the local records of freshwater sponges in Scotland appear to be neither 

 numerous nor altogether trustworthy, I have thought it worth while to 

 publish the following notes, which are based on specimens submitted to m.e 

 by Sir John Murray and Mr. W. Evans and on others found by myself during 

 a recent visit to Scotland. I do not think it probable that the two species 

 here recorded exhaust the list of those that occur, but few naturalists have taken 

 the trouble to collect the Spongillinse of Great Britain, which are therefore 

 imperfectly known. Several interesting forms will probably be discovered 

 in the lakes of Scotland and England if stones from the bottom are 

 examined. So far as my own experience in Scotland and India goes, the 

 under surface of stones from lakes is a favourite station for the less 

 conspicuous and smaller species, which are in many respects the most 

 interesting. These are not always easy to distinguish at sight from patches 

 of algse, but their gritty constitution, due to the spicules of which their 



