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six inches in length, attached at the bottom of the water to stones or aquatic 

 floating plants : examined under the microscope, these filaments present segments 

 nearly as wide as they are long. After the emission of the colouring matter, the 

 filaments become of a clear green ; a portion of the tube is emptied of the endo- 

 chroma which filled it, forming masses of a certain consistence, often separated at 

 small distances. In the empty portions, no traces of the segments can be distin- 

 guished on the external tube. 



The singular coloration produced by this Oscillaria takes place almost instantly 

 on its being gathered ; and it is impossible to transport any mass of it without 

 their becoming immediately decomposed. If specimens preserving their original 

 colour are required, they must be prepared on mica, or paper, in the water in 

 which they were found at the moment of their being gathered. In all cases, on 

 their becoming dried, it colours paper with blue zones ; it also exhales a sharp 

 ammoniacal odour, very different from its congeners. 



De Bribisson and Lenormand discovered this Oscillaria in the month of Sep- 

 tember, 1825, in the River Orne, near Falaise ; it reappeared in 1826, since 

 which it was vainly sought for, when again this year it was abundantly found, in 

 the month of July, in the same river. 



Specimens have been forwarded to Mr. Duby, while publishing his Botanicon 

 Gallicum, mentioning the phenomenon of coloration above stated, which his de- 

 scription does not correctly convey in these words : — Filamentis : demum lilaci- 

 nis aquam purpurio et violaceo tingentibus. 



Other Oscillaria? imgart the purple or blue tinge or water on their decomposition, 

 but we have never observed the two shades existing at the same moment, as in the 

 species now described. 



Mr. Leclencher has addressed de Blainville on the subject of the Spi' 

 rula. He has succeeded in taking, on the Bar of Senegal, the animal inhabiting 

 that mollusc, in a sufficiently perfect state to enable him, by a comparison with 

 others possessing the mutilated parts, to complete a description of the whole. He 

 has observed that the Physalioe feed commonly upon these animals, which ac- 

 counts for the number of their shells and the rarity of the animal in a living state. 

 In addition to the description already given by naturalists, Mr. Leclencher adds, 

 that, independent of the lateral lobes which terminate the animal, two fins may be 

 distinguished, so placed that only a small portion of the shell is exposed. The 

 eyes appear large, and enclosed in a cartilaginous orbit. The lower part of the 

 neck presents the funnel shape usually seen in cephalopids. 



