156 EDWARD B. POULTON. 
fact which will be established below that the corresponding 
glands of the general body surface of this animal bear a con- 
stant relationship to the larger hairs. 
TV. Tue Hairs oF Oty anv YounG ORNITHORHYNCHUS. 
1. Historical, by W. Blaxland Benham, D.Sc. (Lond.), 
Hon. M.A. (Oxon.), Aldrichian Demonstrator in Com- 
parative Anatomy in the University of Oxford. 
The fact that Ornithorhynchus possesses two kinds of 
hair, larger and smaller, was known to Blumenbach (1) and to 
Home (2). The latter also recognised the peculiar character 
of the larger hairs. He writes (p. 69), “‘The hair is made up 
of two kinds: a very fine thick fur half of an inch long, and a 
very uncommon kind of hair three-quarters of an inch long; 
the portion next to the root has the common appearance, but 
for a quarter of an inch towards the point it becomes flat, 
giving it some faint resemblance to very fine feathers.” Later, 
Glockner (3), in a very brief note describes the larger hair in 
somewhat similar terms. In 1823 van de Heeven (4) repro- 
duced Péron’s (5) figures of these hairs; the figures are very 
small, but are the first published, and show the characteristic 
flattening, the narrow stalk, and pointed free end. 
In his monograph, Meckel (6) makes no addition to our 
knowledge of these structures. 
In 1859 Leydig (7), in his classic paper on the Mammalian 
coat, is the first to record the fact that the smaller hairs are 
in bundles—several in each follicular neck—and points out 
that each hair has nevertheless its own special follicle opening 
into the bottom of the common pit. He also states that the 
large spiny hair is surrounded by the bundles of small ones, 
and he gives a figure (pl. xx, fig. 7) of the arrangement, and 
shows the sebaceous glands to each hair and the sweat gland 
accompanying the large one. 
These facts are confirmed by Welcker (8), a few years later, 
who gives measurements of the hairs, the smaller being ‘007 
mm. in diameter, the larger ones ‘(045 mm. across. He too 
