478 MR. R. I. POCOCK ON THE 
Judging by feel and by the parts of the interior of the 
appendage exposed by cuts, it would appear that the organ is 
solid and composed of very delicate, loose, areolar tissue. Injection 
of water or air through a cut upon the surface caused immediate 
and extensive inflation of this tissue, with the exertion of very 
little force. Protrusion may, therefore, he due to the infusion of 
fluid (lymph ?) into the substance of the organ, though possibly 
inflation of the above-mentioned pit in the naso-pharynx may be 
accessory to the protrusion by exerting pressure upon the fluids 
contained in the more distal parts of the appendage. 
On the Feet of Domestic Dogs. 
(Text-figures 1-3.) 
Mr. R. I. Pocock, F.R.S., F.L.S., F.Z.S., Curator of Mammals, 
exhibited a series of lantern-slides illustrating some points in the 
structure of the feet of domestic breeds of dogs (Canis familiaris), 
and remarked :— 
“‘ According to F. Cuvier and Geoffroy St. Hilaire (Hist. Nat. 
Mamm. il. no. 166, 1820), the interdigital integument of New- 
foundland dogs extends almost to the claws and widens to such 
an extent as to make the feet palmated. In this respect, 
according to these authors, the feet of this breed differ from 
those of the majority of breeds in which the web in question is 
of small extent and reaches only as far as the origin (proximal 
end) of the second phalanx ; but, they add, ‘the peculiarity found 
in the Newfoundland dog is not restricted to that breed, but is 
observable in several of our [French] breeds, and especially in 
those not belonging to the category of running dogs.’ St. Hilaire 
restated the fact about the feet of the Newfoundland dog in 
1862 (Hist. Nat. Gén. iti. p. 450). 
In ‘The Variation of Animals and Plants under Domesti- 
cation,’ 1. p. 49, ed. 1905, Darwin, after referring to St. Hilaire’s 
later work, wrote: ‘In two Newfoundland Dogs which I 
examined, when the toes were stretched apart and viewed on the 
underside, the skin extended in a nearly straight line between 
the outer margins of the ball of the toes, whereas in two terriers 
of distinct sub-breeds, the skin viewed in the same manner was 
deeply scooped out.’ 
This description is not very intelligible. It neither confirms 
nor contradicts Cuvier’s statement, because the point on the 
margin of the balls of the toes to which the skin was attached is 
not given. Moreover, no web can extend between the outer 
margins of the toes. It must stretch across the middle line 
between the third and fourth toes, and from the outer margins 
of the latter to the inner margins of the second and third, 
respectively. Setting these difficulties aside, however, it will be 
seen that Darwin did not allude to any difference between the 
