BILL AND HAIRS OF ORNITHORHYNCHUS PARADOXUS. 147 
W. ON. Parker.— Brit. Association Reports,’ 1891, p. 693. Compares the 
snout with that of the young Echidna. 
W. N. Parxer.—‘On some Points in the Structure of the Young of 
Echidna aculeata,” ‘Proc. Zool. Soc. Lond.,’ read January 16th, 
1894, and to be published shortly. Compares with young Nchidna, 
especially as regards ‘“ Jacobson’s organ,” a section of which is 
figured. 
BE. B. Poutron.—‘ Proc. Roy. Soc.,’ 1888, xliii, p. 353. Describes the true 
teeth, and figures a section of one. 
E. B. Poutron.—‘ Quart. Journ. Mier. Sci.,’ 1888, vol. xxix, p.9. Describes 
the true teeth, and figures their appearance, in sections, and in 
minute structure. 
R. WirepersHEm.—‘ Zeit. f. wiss. Zool.,’ liii, 1892, suppl., p. 43. Describes 
and figures the pelvis. 
This paper having been prepared for the press at a time of 
great pressure, my friend Dr. Benham has very kindly relieved 
me of the labour of writing the historical part of the two latter 
sections. I also wish to thank my friend Professor Howes for 
kindly suggesting certain lines of recent research which bore 
upon the subject. So far as the earlier sections are concerned, 
with the exception of Wilson’s and Martin’s recent paper there 
is no other record worthy of mention. 
II. Tue PusH-rops. 
It will not be necessary to describe the histological details 
of these structures at any great length. Reference to Pl. 14 
and to the full descriptions will be sufficient. I shall therefore 
chiefly dwell upon the points which are not touched by Wilson 
and Martin, or in which my interpretation differs from theirs. 
The proportion of these structures to the gland-ducts varies 
in different parts. Thus on the presumably highly sensitive 
ridges within the lower jaw the former are the more numer- 
ous, as may be seen by glancing at fig. 5, where the push- 
rods are seen in section as circles. On the external surface 
of the bill, however, these proportions are usually reversed. 
In relation to the sensitive condition of the bill we learn 
with great interest that it is, in the living state, covered 
with “smooth, soft, and humid skin” (“Anatomy of the 
