BILL AND UWAIRS OF ORNITHORHYNCHUS PARADOXUS. 159 
successional hair, which is to be met with in nearly every sec- 
tion, emerging from the same follicular mouth in front of, and 
therefore overlapping, the base of the old one. The succession 
of smaller hairs is less rapid, but one or more younger, growing 
hairs are to be seen in every bundle. The exact relationship 
in two instances can be made out by ascertaining the propor- 
tion of dark circles (sections of young hairs) to the smaller 
unpigmented circles (sections of bases of old hairs) in each of 
the four bundles in figs. 17 and 18 of Pl. 15, which contains 
all the figtires illustrating the structure of the hair of Ornitho- 
rhynchus. The proportions in the four bundles of three other 
groups were as follows: 
First GRovp. 
Bundle I. ; . 1 young hair to 9 or 10 old. 
ea Waa : On sg, Shales’ £0 Se, 
ro TE ; ea. nal te 1 5 
arte LNs 3 5,  hairsito By aay 
SEcOND GROUP. 
Bundle I. : : . 1 young hair to 8 old. 
Het ae : Oe oe a DBIS:LOlS. 3s, 
hie : : Sle ae Tal cOn Ory 55 
as ing ge HAIESL6O 7) 55 
THIRD GROUP. 
Bunde I. : ; . 2 young hairs to 7 old. 
vat pili tien F ; tbs sees Lair etO, gaya 
” TE . . ° = ” oF) 8 ” 
cpallNat . P aoe. hairsstonl 0)... 
The proportion of young hairs was ascertained in each case 
by counting the numbers of dark and light circles in a section 
taken sufficiently near the surface of the skin to bring all the 
hairs of a bundle into a common follicular neck, as in fig. 17. 
These figures, together with the number shown in fig. 17, 
prove that, at any rate in the dorsal region, Leydig’s estimate 
of the number of small hairs in a bundie is too small, while 
that of Welcker is far too large. 
Each group of hairs is attended by a single gland exactly 
VOL. 36, PART 2,—NEW SER. M 
