124 PROCEEDINGS OF THE MICROSCOPICAL SOCIETY OF LONDON. 



only in the lines which are found on the surface of the superior layer of 

 the scale. M. Agassiz has then fallen into a great error relative to the 

 manner in which I examined the structure of the scales. January, 1840, 

 p. 58, 62. 



[From the Comptes Rendus.~] 



Infusoria of Rock Salt. M. Marcel de Serres communicated a note 

 on the subject of the observations which he is making along with M. 

 Joly. In the specimens of rock salt of a tolerably decided greenish 

 colour, brought from Cardona (Spain), the Infusoria appear more rare, 

 of a smaller size, and less distinct than in the specimens of a red co- 

 lour before examined. 



This, says M. Marcel de Serres, finds an explanation in M. Joly's 

 previous observations on the change of tint, which the Infusoria that 

 colour our salt marshes undergo by age. These animalcules, which are 

 white at their birth, become green in their middle age, and do not till 

 their adult age take the purple tint which makes them so remarkable. 

 In general, the green Infusoria are not so often seen as the red in salt 

 marshes, which seems to indicate that these monades remain but a short 

 time in their middle state. 



We have found the same Infusoria in the Argilo- calcareous marls, 

 which are found at Cardona beneath the rock salt. In this locality they 

 have their beautiful purple tint, but they are in too small numbers 

 to communicate it to the mass of marl, which is of a greyish hue. This 

 fact also proves, that in the ancient world, as in the present, the ani- 

 malcules were precipitated after death to the bottom of the waters in 

 which they had previously lived. March 16, 1840. 



Theory of Digestion, $c. The Royal Academy of Sciences and Belles 

 Lettres at Brussels, offers a prize for the best essay on this subject ; 

 embracing, more particularly, a microscopic examination of the chyme, 

 and to determine the relation which subsists between the parts com- 

 posing the chyme and certain aliments; such as albumen, gelatine, 

 milk, and its products, &c. 



The prize offered by the Academy, is a gold medal of the value of 

 600 francs. It is requisite that the memoir be legibly written in Latin, 

 French, or Flemish, and that it be forwarded, free of expense, before the 

 1st of February 1842, to M. Quetelet, Perpetual Secretary to the 

 Academy. 



PROCEEDINGS OF THE MICROSCOPICAL SOCIETY OF LONDON. 



August l8th.R. H. Solly, Esq., F.R.S. #c., in the Chair. 



A PAPER was read by Mr. John Quekett, ' On the Anatomy of four 

 species of Entozoa of the genus Strongylus, from the Delphinus Pho- 



