J. S. Manson 61 



numbers arc small, yet it is very significant that the whole family should 

 be consecutively and uniformly affi'ctetl. 



The result of the matings of these DR members with RR normals 

 is shown in the pedigree to number 40 df whom LS are affected, 18 un- 

 affected and 4 doubtful. These figures accord with what might be 

 expected in a Mendelian ratio, for DR and RR unions. 



The nature of the abnormality seems complex and irregular. In 

 only three of the descendants of II. 7 does the abnormality ap])ear 

 complete in the 4 limbs, and this was in the III. 15, IV. 34 and the 

 great grand-daughter — V. 3. In the descendants of II. 2 one, two, and 

 even three limbs escape, and in the bony abnormality itself there is 

 some variation in the affected members. 



The polydactylism in the feet is apparently due to an extra digit 

 interpolated between a normal 4th and .oth digit. In only one of the 

 skiagi-aphs, F, , does this extra metatarsal appear to have a tarsal articu- 

 lation. In the others it distinctly arises either from the base or the 

 shaft of the 4th metatarsal, or is represented by a fragment of bone 

 l3'ing between the 4th and a normal 5th metatarsal having an articula- 

 tion with the cuboid. In III. 15 this piece of bone has partially or 

 completely fused with the 5th metatarsal and forms its articular head. 



In the hand the skiagraphs show a condition of incomplete poly- 

 dactylism, but it is difficult to decide whether the suppressed extra digit 

 lies between a normal Srd and 4th digit or between a normal 4th and 5th. 

 Skiagraphs of the right hands of III. 15 and IV. 6 show a fragment of 

 a metacarpal lying between apparently normal 3rd and 4th metacarpals, 

 and Skiagraph J (Plate XIX) of infantile hands tends to confirm the 

 impression that the suppressed or aborted digit lies between a normal 

 3rd and 4th finger. 



On the other hand Skiagraph F (Plate XVII) shows a piece of bone 

 in association with the proximal phalanx of the right 4th digit lying 

 towards the 5th digit. All the skiagraphs show that the 4th digit 

 presents the chief abnormalities of irregularly shaped phalanges, while 

 the phalanges of the 3rd digit are of normal shap)e. These appearances 

 on both hands and feet suggest that in this family the polydactylism 

 present is due to the partial or complete' reduplication of the 4th digit 

 of both hanils anti feet. 



With regard to the syndactyly, skiagraphs of IV. K! and IV. (i 

 (left hand) show that the webbing of the fingers occurs without evident 

 bony abnormality. In IV. 14, where the polydactylism of the feet is 

 most complete, webbing is not limited to the 4th, 5th and 6th toes, but 



