18 I'ELAUJC CONl'EKVyl': AMJ IiNFUSOUIA. 



beautiful carmine-red fibrous matter, which stains 

 ivory and paper in so permanent a manner, that 

 the tint is retained with all its brightness to the 

 present day : I am quite ignorant of the nature and 

 use of this secretion. I have heard from Dr. Allan 

 of Forres, that he has frequently found a Diodon, 

 floating alive and distended, in the stomach of the 

 shark ; and that on several occasions he has known 

 it eat its way, not only through the coats of the 

 stomach, but through the sides of the monster, 

 which has thus been killed. Who would ever have 

 imagined that a little soft fish could have destroyed 

 the great and savage shark 1 



March ISth. — We sailed from Bahia. A few 

 days afterwards, when not far distant from the 

 Abrolhos Islets, my attention was called to a red- 

 dish-brown appearance in the sea. The whole sur- 

 face of the water, as it appeared under a weak lens, 

 seemed as if covered by chopped bits of hay, with 

 their ends jagged. These are minute cylindrical 

 confervae, in bundles or rafts of from twenty to sixty 

 in each. Mr. Berkeley informs me that they are the 

 same species (Trichodesmium erythrasum) with that 

 found over large spaces in the Red Sea, and whence 

 its name of Red Sea is derived.* Their numbers 

 must be infinite : the ship passed through several 

 bands of them, one of which was about ten yards 

 wide, and, judging from the mud-like colour of the 

 water, at least two and a half miles long. In al- 

 most every long voyage some account is given of 

 these confervffi. They appear especially common 

 in the sea near Australia ; and off Cape Leeuwin 

 I found an allied, but smaller and apparently dif- 

 ferent species. Captain Cook, in his third voyage, 



* M. Montagne, in Comptes Rendus, &c., Juillet, 18i-4 ; and 

 Annal. des Scienc. Nat., Dec, 1844. 



