282 
DR, U. PRITCHARD ON THE ORNITHORHYNCHUS PLATYPUS. 
4. Triangular cartilage. 
5. Nerve, ( b ) ganglionic cells, (c) fibres passing through cartilage. 
6. Tegmentum, (e) folds. 
7. Organ of Corti, (f ) membrana basilaris, (g) membrana tectoria, (d) 
bone. 
Postscript. 
(Added January 26, 1881.) 
To prevent misunderstanding, it may be as well to state that the object of this 
memoir being the description of the cochlea of the Ornithorhynchus and its comparison 
with that organ in the ordinary Mammal and Bird, I have purposely omitted the 
description of these last, except where necessary for such comparison. 
Very complete descriptions of these will be found in Quain’s ‘ Elements of Anatomy,’ 
8th edition, vol. ii., for the Mammal; and in Paul Meyer’s ‘ Labyrinthe Mem- 
braneux du Limagon chez les Reptiles et les Oiseaux, 1876’ (published by 
J. B. Bailliere et Fils, Paris), for the Bird and lower vertebrates. 
Since presenting this memoir I have discovered a second row of hair cells to the 
outer side (corresponding to inner side of ordinary Mammals) of the rods of Corti 
(see Plate 46, 12 , fig. 6, ^). 
This is the only animal in which I have seen an additional row of hair cells in this 
position; nor, indeed, am I aware of such a peculiarity having been noticed by other 
observers in any form of cochlea. 
