391^ Scientific Notices — Zoology, [Nov. 



than 0*16 by calcination. The powder dried, but not calcined, 

 rapidly absorbs water when put into it, or when it is left exposed 

 to moist air. Sulphuric acid readily acts upon it, even cold ; 

 it separates gelatinous silica, which dissolves perfectly in the 

 alkalies. By analysis after drying in a stove it yielded 



Silica 44-94 



Alumina 39*06 



Water 16-00 



100-00 



The alumina contained a little iron, which renders it probable 

 that the blue tint of the mineral may be owing to the presence 

 of phosphate of iron.-— (Annales de Chimie.) 



7. Cold produced bi/ Combination of Metals. 



According to M. Dobereiner, when 118 parts of tin, 207 of 

 lead, 284 of bismuth, and 1617 of mercury were mixed at the 

 temperature of about 65° Fahr. it immediately fell to 14°. — 

 (Ibid.) 



Zoology. 



8. Notice on the Digestive Organs of the Genus Co7natula of 

 Lamarck f and on the Crinoidea of Miller. By J. E. Gray, 

 Esq. FGS. 



Having lately occasion to examine a specimen of Comatula 

 preserved in spirits, I was struck by observing that the proboscis- 

 like tube described by Peron, Lamarck, Miller, &c. as the 

 mouth of this animal, was not situated in the centre of the body, 

 but at an intermediate distance between the centre and the 

 margin, on the smooth place intermediate between the arms. 

 On examining the centre, I found a distinct, rather large, aper- 

 ture, which certainly led on to the intestinal cavity. Now from 

 the situation of the latter opening, which is similar to the mouth 

 of Asterias, and from its form, I am inclined to consider it as the 

 mouth. This hole could only have escaped the view of the 

 above-quoted authors by their having examined dried specimens 

 only. This central aperture is pentagonal, surrounded by a 

 fringe which diverges at its angles, sending out towards the 

 margin, and dividing before it reaches the edge so as to give a 

 double fringe-line to each arm, which extends up its centre, and 

 sends off a process to the inner edge of each of the fingers, so as 

 to ciliate their inner edge. This continuation of the abdominal 

 inte«-uments is doubtlessly intended for the motion of the arms. 

 1 was not enabled to examine the internal structure of the speci- 

 men, so that I cannot speak with certainty with regard to the 

 uses of this aperture, but the central one did not appear to be 

 provided with any teeth. The tubular process is contracted at 



