METACHROSIS. 
225 
parent, urge the blood to rush more upon the skin, 
and, according as the fluid fills itself or empties itself 
of air, its colour becomes more or less lively.’ By 
the investigations of Mr. Houston (Trans, of Roy. 
Irish Acad. xv. 177.) the proximate cause of change- 
ability is connected with the circulatory system. The 
skin of the changeable Saurians is not only very 
thin, but highly vascular; and he thinks that the 
colour of the blood appearing through the semi- 
transparent covering, and being variously modified by 
its more permanent hues, is of itself sufficient to 
account for every diversity of tint which the Chame- 
leon can assume. He maintains the opinion that 
these effects are produced by vascular turgescence, 
‘ just as the increased redness in blushing is caused 
by a rush of blood to the cheeks.’ I would seek in 
addition an illustration from the changeable hues in 
the caruncles of the Turkey. There, too, aeration 
produces a diversity of influences on the circulatory 
system. The red hlood distributed through these 
parts increases and diminishes its intensity of tint 
by the different aerations at the caprice of the bird, 
and, being sometimes wholly deprived of its red 
particles, flows colourless, as the fluids circulate in 
the white of the eye.” 
I have seen the Pearly-bellied Anolis only in 
Westmoreland. In those parts of the coast of St. 
Elizabeth which He to the eastward of Black River, 
and in the district around Spanish-town and Kings- 
ton, it appears to be replaced by the Zebra Anolis, 
{A, maculatus), a very handsome species, of rather 
larger size, with fine contrasts of pale yellow and deep 
