CASE OF SARCINA VENTRICULI. 357 



yellow or brown. When carefully examined under favourable 

 circumstances the cell- walls appeared rigid, and could be 

 perceived passing from one flat surface to the other as dis- 

 sepiments. These dissepiments, as well as the transparent 

 spaces, were from compression of contiguity rectilinear, and 

 all the angles right angles ; but the bounding cells bulged 

 somewhat irregularly on the edges of the organism, by reason 

 of the freedom from pressure. 



These circumstances gave the whole organism the appear- 

 ance of a wool-pack, or of a soft bundle bound with cord, 

 crossing it four times at right angles and at equal distances. 



From these very striking peculiarities of form, I propose 

 for it the generic term SARCINA.** 



Perfect individual SAUCING, of the species now under 

 consideration, vary from 800 to 1000 of an inch linear 

 along each of their sides. They are, as has been stated, 

 slightly brown or yellow under a high power under moderate 

 glasses they appear dark, and are defined with difficulty on 

 account of the frequent reflections of the light by the dis- 

 sepiments. Iodine does not react with them, as with starch, 

 but tinges them deep brown or yellow. They shrivel but 

 slightly in alcohol. In nitric acid, even after boiling for some 

 time, the sixteen ternary squares retain their relative 

 position, but diminished and shrivelled, appearing like minute 

 crystalline granules arranged in a square. So persistent are 

 those arrangements of granules in boiling nitric acid, that I 

 at one time suspected the existence of silicious loricae, or 

 isolated raphides, but as I could not detect the same forms or 

 arrangements in the ashes of the evaporated and calcined fluid, 

 I do not now believe in their existence. 



This species of SARCINA, therefore, consists of sixteen four- 

 celled frustules, imbedded in a square tablet of a transparent 



SARCINULA would have been more appropriate, had not Lamarck already 

 applied the term to a genus of polyps. 



