78 ABNORMAL CONDITIONS OF THE LIMBS. 



phalanges fused into a single bone. This condition pro- 

 bably arises from imperfect differentiation of the digits 

 and persistence of the primitive connecting web in which 

 they are formed. Presented by Sir W. Blizard. 



324. The other manus of the same animal ; the functional digits 



are included in a single hoof. 



Presented by Sir W. Blizard. 



325. A precisely similar specimen. 



Presented by Sir E. Homey Bart. 



326. A similar specimen in which the digits are included in a 



single narrow pointed hoof. Hunterian. 



b. Perodactylus. 

 Syn. Ectrodactylie, Geoff. 



^ 



This condition exhibits arrest accompanied by atrophy. 



327. The hands of a full-time Human foetus. The right is pre- 



pared as a skeleton. The thumb of the left hand is 

 represented by an imperfect terminal joint only; this 

 adheres to the hand by a narrow pedicle of. integument. 

 In the right hand the thumb is entirely wanting, and the 

 fifth digit is adherent to the metacarpal bone of the fourth. 

 The union is ligamentous, and the base of the fifth meta- 

 carpal bone has been entirely absorbed. The process of 

 atrophy seen in progress in these digits is precisely 

 similar to that which affects supernumerary digits. In 

 these the phenomenon is observed far more commonly 

 than in the normal parts. 



Presented by R. Partridge, Esq. 



B. Of the Limbs, 

 a. Ischnomelia. 



Where the limb is preternaturally slender,, some of the bones 

 are frequently absent ; the digits are often arrested at an early 

 stage of development. There is usually arrest of other parts ac- 

 companying this condition. A patagium very rarely remains in 

 arrested conditions of the limbs. See No. 329*. 



* See also Gurlt, Path. Anat. der Haus-Saugethiere, ii. p. 118, and 

 Theil ii. tab. iv. fig. 5. 



