OSTEOLOGY. 299 
lishment a number of years ago. The second anomalous specimen is M. C. Z. 
7,009, collected by Dr. Thomas Barbour in Sorong, New Guinea. This specimen 
has the usual three claws on each of the fore feet, but a small extra claw on digit 5 
of each of its hind feet. This extra claw measures 9 mm. in length. There are 
several other cases of variation on record, as follows:— 
Thomas (1907a, p. 499, footnote) records that the type specimen of his 
Acanthoglossus bruijnii bartoni had five claws on both of the fore and hind feet, 
as in the Echidna. Weber (1888) describes at length a specimen in Amsterdam, 
that had five functional claws on both fore feet, and four on each hind foot. 
From his figure it is seen that the supernumerary claw on the hind foot is that 
of digit 5, though in the text, through error, it is given as of digit 1. Its length 
is 15 mm., or less than half that of the fourth claw. Toldt (1906) mentions 
two other abnormal specimens. The first of these is in the Museum at Brussels. 
On digit 1 of the right fore foot isa second phalanx bearing a claw 12 mm. long. 
The left fore foot, however, has but the usual three claws on digits 2, 3, 4, as 
have also the hind feet. The second individual is in the Umlauff museum 
at Hamburg. The left fore foot only of this individual is abnormal in that 
each of the five digits bears a claw. That of digit 1 is short and rounded but 
that of digit 5 is more fully developed, 11 mm. long and 6 mm. broad. The six 
known abnormally clawed individuals of this genus may be tabulated as follows, 
the numeral expressing the presence of a claw on its respective digit. 
Abnormally clawed Proechidnas. 
Specimen. | Right Fore. | Left Fore. | Right Hind.) Left Hind. 
British Museum | iL Bek 1 OF BAS iL, DS iOS ce Gy 
Amsterdam IONS Was 1, 2,3, 4,5 COWBA8 | MBAs 
U.S. N. M. 22,992 \ OO Avi! || OO oea og OPB205. || OP S255 
M. C. Z. 7,009 Wa) 25S) 40 I) Oona 400 |) Oy2-394)5. |) 20,93. 4.5 
Brussels |, a. 235450 0, 2, 3, 4, 0 0) 253; 4, 0 0, 2, 3, 4, 0 
Hamburg | 9, OP Se (0) PA yee 5) 0; 2; 3, 4, 0 0, 2, 3, 4, 0 
Since some twenty-five or more specimens are recorded in which the claw 
formula for each foot is 0, 2, 3, 4, 0, this must be considered the normal condi- 
tion, from which regressive variation sometimes takes place. In case of the 
hind feet, digit 1, as might be expected from its less marked skeletal develop- 
ment, is much more rarely clawed than is digit 5 — in fact there is but one 
recorded case of a claw on the first hind digit. No instance is known of its 
presence without also an accompanying claw on digit 5. No doubt the order 
of disappearance in phylogeny is first claw 1, then 5. The reduction of the fore 
