*K? 



356 MERISTIC VARIATION. [part I. 



digits similarly formed, but in the last the feet are also turned in. Struthers, 

 Edin. New Phil. Jour. , 1863 (2), p. 100. 



As an example of similar and simultaneous Variation in both extremities this is 

 an instructive case. 



(2) Syndactylism. 



Under this name have been described those cases in which two 

 or more digits are to a greater or less extent united together. In 

 their bearing on the morphology of Repeated Parts some of these 

 variations are very instructive. It will be found that the impor- 

 tant considerations in this evidence may be divided into two parts. 

 Of these the first concerns the manner of the variation and the 

 second to the position in which it is most commonly found. 



The manner of union between digits. 



In many cases of union of digits the limb is amorphous ; with 

 these we have now no special concern. In simpler examples the digits 

 may be of normal form but some or all of them may be united by a 

 web of integument for a part or the whole of their length. (For 

 records of such cases see Fort, Annandale, &c). 

 524. But besides these cases of webbing are many in which the union 

 may be of a much more intimate character. Taking the cases together 

 a progressive series may be arranged shewing every condition, beginning 

 from an imperfect webbing together of the proximal phalanges to the 

 state in which two digits are intimately united even in their bones, and 

 perhaps even to the condition in which two digits are represented by a 

 single digit (see No. 529). That the latter condition represents a phase 

 in this series of variations does not seem to be generally recognized by 

 those who have dealt with the subject but it is impossible to exclude it. 



The lower conditions of this variation are sufficiently illustrated by 

 Fig. 104, I and II (from Annandale, Diseases of Fingers and Toes, 

 figs. 39 and 33), shewing cases of medius and annularis partially com- 

 bined for the whole of their length. A higher condition is shewn in 

 Fig. 104, III, in which the same digits are united so closely that their 

 external appearance suggests that only four digits are present in the 

 hand. In this specimen (Annandale, I. c, p. 14) there were neverthe- 

 less five metacarpals, but the first phalanges of III and IV were united 

 peripherally and bore a second and third phalanx and one nail common 

 to them both. The same author (/. c. fig. 44) gives an illustration of 

 such a set of bones from Otto \ 



The following cases are interesting as occurring in Apes. 



o2o. Pithecia satanas (Monkey) : young male having the third and fourth digits of 

 the hand on each side completely connected by a fold of nude skin. The remain- 

 ing digits of the hands and feet were normal. Forbes, W. A., P. Z. S., 1882, 

 p. 442. 



526. Macacus cynomologus : specimen having the fifth finger of the right hand 

 represented by a rudiment only. On dissection the first phalanx of the fifth finger 

 was found to be enclosed with that of the fourth. All the fingers of the abnormal 

 (right) hand were somewhat misshapen and bore several exostoses. ['? congenital 

 variation] Friedlowsky, A., Verh. zool. hot. Ge>>. Wien, 1870, xx. p. 1017, Plate. 



1 I have failed to find the original of this figure in Otto's works. 





