358 STUDIES, SCIENTIFIC AND SOCIAL chap. 



here there is apparently more of regularity and symmetry. 

 The greatest amount of this kind of variation occurs in the 

 sloths, as might be expected when we consider that they 

 are the most abnormal of mammals as regards the cervical 

 vertebrae. In Chapter VIII. numerous cases of super- 

 numerary mammae are recorded, almost all of which are 

 unsymmetrical. The variations in the number or form of 

 the horns in sheep, goats, and deer recorded in Chapter 

 XL show them to be usually more or less irregular. 



Nearly a hundred pages are devoted to the digits (fingers 

 and toes) of mammals and birds, about one hundred and 

 forty cases of variation being recorded. Almost the whole 

 of these present, more or less, want of symmetry, while a 

 large proportion, as the double-handed and double-footed 

 children, and the six or seven-toed cats, can only be classed 

 as monstrosities. 



In succeeding chapters the variations in the antennae 

 and leg-joints of insects ; in the radial parts of medusae 

 and encrinites ; in the medial structures of fish, insects, 

 molluscs, &c., which become sometimes double ; in the 

 eyes and colouration of flatfish ; in duplicate or branching 

 legs of insects and crustaceans ; in extra limbs of batra- 

 chia; and, lastly, double monsters, are all discussed at 

 great length, and are illustrated by a number of very 

 interesting wood-cuts. But almost the whole of these can 

 only be classed as malformations or monstrosities which 

 are entirely without any direct bearing on the problem of 

 the " origin of species." 



Monstrosities have no Bearing on the Origin of Species. 



Nothing can better show the small value of the book 

 from this, which is the author's own, point of view, than 

 the large amount of space devoted to the various mon- 

 strosities of the hands and feet of man and of some of the 

 mammalia. Not only throughout all mammals, but also 

 in the case of birds, reptiles, and amphibia, five is the 

 maximum number of the toes or fingers. These may vary 

 in size or in proportions ; they may be reduced in number 

 by coalescence, or by the loss of the lateral digits ; they 



