chap, xiii.] DIGITS : CAT. 317 



that is, the one next to the digit II, is in some degree shapeless 

 and imperfect, but the external branch is as a digit of the other 

 side in form. Internal to this double digit is a seventh digit, 

 sometimes with two phalanges, sometimes with three, but in either 

 case the claw is as a rule non-retractile, and the digit is in this 

 respect not differentiated as either right or left. Such a manus 

 may be thus represented (cp. Fig. 86 a left manus) : — 



Eight. Eight. Eight. Eigbt. Amorphous Left Indifferent 



V IV III II digit digit digit 



As regards the carpus its changes are like those of the tarsus. 

 When there are six metacarpals there are three carpals in the distal 

 row internal to the magnum. That next the magnum may be 

 supposed to be trapezoid, and the other two may be spoken of as 

 first and second trapezium. In correspondence the length of the 

 scapho-lunar is increased. 



No comment can increase the interest of these curious facts. 

 In the pes, as has been stated, with change in the number of 

 digits there is change in the grouping and symmetry of the series 

 of digits, and in particular the digit having the relations of the 

 index or digit II is formed as the optical image of its neighbour 

 III instead of forming a successive series with it. There is thus a 

 new axis of symmetry developed in the limb, passing between the 

 parts which form the digits II and III of the normal. 



The evidence of the above statements may now be given. 



t72. Cat having the digital series of each extremity abnormal, being 

 that preserved in the Coll. Surg. Mus., Teratological Catalogue, 

 1872, Nos. 305 and 306. 



Right pes (Fig. 85, II). Digits III, IV and V normal right 

 digits. Internal to these are two digits each having three phalanges 

 and claws. That lettered d 1 is formed as a left digit but d 2 is al- 

 most indifferent, the second phalanx being slightly hollowed on the 

 inside. Internal to the external cuneiform there are three small 

 bones, of which the inner two together bear the digit d 1 . [This is 

 the Condition II of the pes.] 



Left pes has the same structure as the right so far as can be 

 seen from the preparation (in which the muscles remain). The 

 digits III, IV and V are normal left digits, but internally to them 

 there are two digits each with three phalanges, of which the 

 external is an indifferent digit, while the internal is formed as a 

 right. [Condition II of the pes.] 



Left manus. The digits II, III, IV and V are normal. But 

 the carpal of the distal series (trapezoid) which bears the digit II 

 is imperfectly separated from a similar bone placed internal to it. 

 This second part of the trapezoid bears a metacarpal which 

 articulates with a full-sized digit of three phalanges formed as a 

 right digit. From the external side of the first phalanx of this 



