226 Miscellaneous. 



of the sea, and even less remarkable for its beautiful red colour than 

 for its prodigious fecundity. 



3. That the reddening of the waters of the lake of Morat by an 

 Oscillatoria which DeCandolle has described, has the nearest re- 

 lation to that of the Arabian Gulf, although the two plants are 

 genetically very distinct. 



4. That as we may well suppose, according to the accounts of 

 navigators, who mention striking instances of the red colouring of 

 the sea, these curious phenomena, though not observed till quite 

 recently, have nevertheless without doubt always existed. 



5. That this unusual colouring of seas is not exclusively caused, as 

 Peron and some others seem to think, perhaps as being chiefly zoolo- 

 gists, by the presence of mollusca and microscopic animalcules, but 

 that it is often also due to the reproduction, perhaps periodical and 

 always very prolific, of some inferior Algae, and in particular of the 

 species of the singular genus Trichodesmium. 



6. Lastly, that the phenomenon in question, although generally 

 confined between the tropics, is however not limited to the Red Sea, 

 nor indeed to the gulf of Oman ; but that, being much more general, 

 it is found in other seas, for example in the Atlantic and Pacific 

 Oceans, as appears in the * Journal of Researches ' by Mr. Darwin, 

 and from the unpublished documents of Dr. Hinds, communicated 

 by Mr. Berkeley, and from which the following extract is given : — 



" Dr. Hinds, who sailed in the ship Sulphur, sent to explore the 

 western coasts of North America, first observed on the 11th of 

 February 1836, near the Abrolhos Islands, the same Alga doubtless 

 which Mr. Darwin saw at the same date. This Alga was again seen 

 many days running. Some specimens of it having been brought to 

 Dr. Hinds, he perceived that a penetrating odour escaped from it 

 which had before been thought to come from the ship ; this odour 

 much resembled that which exhales from damp hay. In April 1837, 

 the Sulphur being at anchor at Libertad, near St. Salvador, in the 

 Pacific, Dr. Hinds again saw the same Alga. 



" A land breeze drove it for three days in very thick masses about 

 the ship. The sea exhibited the same aspect as at the Abrolhos 

 Islands, but the smell was still more penetrating and disagreeable ; 

 it caused in a great many persons an irritation of the conjunctive, 

 followed by an abundant secretion of tears. Dr. Hinds himself expe- 

 rienced it. The Alga in question constitutes a distinct species of the 

 genus Trichodesmium, and is named by M. Montagne T. Hindsii. It 

 differs from that of the Red Sea both in dimensions and smell." — 

 Comptes Rendus, July 15, 1844. 



r^ 



M. DB QUATREFAGES ON GASTEROPOD MOLLUSCA. 



M. de Quatrefages, at present engaged in the pursuits of natural 

 history on the coasts of Sicily in company with M. Milne Edwards, 

 has sent to the Academy of Sciences a notice on the group of 

 Gasteropod Mollusca for which he has proposed the name of Phle- 

 benterata, and of which the following is an abstract. 



1 . In all the Phlebenterate Gasteropod Mollusca, the function of 



