SUPPLEMENTARY NOTES. 453 



skin, in consequence of the resemblance in the structure of its ribs 

 to that of the ribs of the Chameleon, 



See Penny Cyclopaedia, Vol. VI. p. 474, et seq. 



P. 166. A remarkable exemplification of the exquisite Power 

 of the human hand has been communicated to me by Mr. James 

 Gardner, of Regent Street, London, from whom I learn that he 

 has with his own hand, aided by the sense of touch alone, and 

 with his eyes shut, ruled parallel lines, which being examined with 

 a micrometer, were found to be at the exact distance of 2 t'j o °^ 

 an inch from one another. With his unarmed eye he cannot dis- 

 tinctly see lines that are more distant from one another than ~jy 

 of an inc?i. In this case the sense of touch is more acute than 

 that of sight in the ratio of 8 to 1. 'Mr. Gardner is also able, 

 without the assistance of any instrument, to draw a perfect circle 

 or a perfect ellipse, moving his hand on the wrist as a centre. 



P. 222. " The senses of Conchifersmust be very confined; and 

 indeed there is no good ground for attributing to the generality 

 of them any thing beyond a sense of touch and taste. That most 

 of them may be conscious of the presence or absence of light is 

 possible. "Not having any especial organs for seeing, hearing, 

 or smelling," says Sir Anthony Carlisle, speaking of the common 

 oyster in his Hunterian Oration (1826,) "the creature is limited 

 to perceive no other impressions but those of immediate contact; 

 and yet every part of its exterior seems to be sensible to light, 

 sounds, odours, and liquid stimulants. It is asserted by fisher- 

 men, that oysters, in confined beds, may be seen, if the water is 

 clear, to close their shells whenever the shadow of a boat passes 

 over them." 



" M. Deshayes goes so far as to say that no especial organ of 

 sense can be detected among them, unless, perhaps, those of 

 touch and taste; but we must not forget what have been called 

 the eye-specks in the Pecten, to the animal of which Poll gave 

 the name of Argus, from the supposed number of its visual organs. 

 The pectens are free swimmers, and, from their rapid and desultory 

 motions, we have heard them termed the butterflies of the ocean. 

 The manner in which these motions are executed, especially 011 



