240 NATURAL SCIENCE. Sept.. 1893. 



subject, the greatest care should be taken to avoid conveying, by implication or by 

 direct statement, an erroneous idea as to who was the discoverer of any new fact of 

 importance or the originator of a theory. For instance (I am speaking, of course, 

 of the review, and not of Mr. Pocock's valuable paper), it is stated, page 448, that 

 " On these grounds he [Pocock] considers the scorpions as the lowest living branch 

 of the arachnid stem, in opposition to the views of Thorell and others, who have 

 regarded them as the highest. There can be no doubt that Pocock's opinion will 

 meet with general acceptance among biologists. Deriving the arachnid orders 

 immediately from an ancestor with a long abdomen of twelve segments and a telson, 

 Pocock indicates the modifications which have probably occurred in each group . . . 

 nearly related to the Pedipalpi . . . are the Solifuga; . . . , on a higher branch . . . 

 come the harvest men (Phalangida) . . , from these the mites (Acari) ... a degraded 

 offshoot." Turning to Lankester (/oc. aY., p. 644) we find, " the Scorpions, having 

 once been developed, appear to have given rise to the whole series of living 

 Arachnida, to the Pedipalpi first, and through these to the Araneina, and through 

 the Araneina to the Acarina ... we have to admit a very extensive process of 

 degeneration . . . leading from the Scorpion to such Acarina as Demodeae ..." 



In the discussion (p. 450) on the light thrown by palaeontology " upon the 

 question whether the lung-bearing cr tracheate orders of arachnids are the more 

 primitive," no notice whatever is taken of the mass cf evidence collected by 

 Professor Lankester showing the relationship between the Scorpions and the 

 extinct Eurypterina and Trilobita. 



On page 449, we are led to believe that Mr. H. M. Bernard originated the view 

 that the " spinning-glands, coxal glands, and poison-glands" were derived from the 

 "ventral setiparous glands of an annelid ancestor," a theory put forth by Eisig 

 in his famous Monograph of the Capitellidae. 



The Museum, Oxford. E. S. Goodrich. 



" Unilateral " Sleep in Animals. 



The late Sir Emerson Tennent, in his " Natural History of Ceylon " (1861) at 

 page 279 observed that each eye of the Chameleon (Chameleo vulgaris, Daud.) had 

 not only a separate action quite independent of the other eye, but that also one side 

 of its body appeared sometimes to be asleep while the other side was vigilant and 

 active. 



Hence, while one side of the Chameleon was green, the other was red. 



It is said that the Chameleon is unable to swim because the muscles of its two 

 sides cannot act in concert. Is this true ? 



Similarly some other accurate observers, including Matthias Dunn of Mevagissey, 

 suspect that certain fish can secure partial sleep with one eye at a time. 



I should be grateful for further information and references as to whether other 

 animals have been observed in this alleged condition of one-sided sleep while the 

 other side of their body continues awake. 



30 Sussex Square, Brighton. J. Lawrence Hamilton, M.R.C.S. 



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