of Fingers and Toes, and of the Phalanges, in Man. 107 
one phalanx, in most of them two phalanges. Among the 
hereditary cases, in case 19 (a) there is a metacarpal bone 
besides two phalanges ; and, in case 18 (a), the same occurs 
in both hands, while on the six-toed foot it has not extended 
to the metatarsal bone. In case 17 (a) one of the thumbs 
on each hand presents three phalanges without an additional 
metacarpal, while the two great toes have, on both feet, two 
phalanges each, and one foot has an additional metatarsal 
bone. In case 17 there is an additional metacarpal bone 
and three phalanges. We do not know how it was with 
the ancestors of these cases, but in none of the cases of 
non-hereditary variation did it extend so deeply into the 
limb.* 
When the variety is transmitted it is on the same side of 
the limb. In case 15, the additional digit was external, 
both on the hands and feet, in all the ramifications of the 
descent. Also in case 20. In cases 17, 17 (a) 18, and 
18 (a), in which the variety is derived from a common 
ancestor by different lines of descent, it is on the inside of 
the hand or foot, or on the inside of both hand and foot. 
Also in case 16. In none of the cases was it external on 
one limb and internal on another limb of the same person, 
or in the same family. Incase 8, of two children in the 
same family, one had an additional little finger, the other 
an additional thumb, but the case is one of the non-heredi- 
tary group, and there is the curious fact that they were the 
children of different fathers, though of the same mother. 
The influence of sex does not appear to any marked extent 
in the hereditary transmission in the above cases. 
Diminution in the Number of the Digtts—Diminution in 
* When the additional digit is supported, as it generally is when well 
formed, on one end of a more or less bifurcated metacarpal or metatarsal 
bone, it might be supposed that this indicated the original presence of an 
additional metacarpal or metatarsal bone, which had become more or less con- 
fluent with the next, as in the development of the metacarpus and metatarsus 
in the ruminant. But while this can be easily shown in the ruminant, there 
is no proof that here there is anything but a more or less extensive bifurcation 
of one bone. In the dissection of the left foot in case 21, in which the fourth 
and fifth toes were partially united and supported on one metatarsal bone, the 
fifth metatarsal being wanting, the fourth metatarsal was twice the normal 
thickness, but presented no trace of double origin, externally or internally, 
although the foot was that of a new-born child, 
