XVII. On the Osteology of the Kagu (Rhinochetus jubatus). 
By W. K. Parker, /.B.S., F.Z.8. 
Read January 9th, 1868. 
[Piates XCI., XCII.] 
IN the Proceedings of this Society for 1864 (pp. 70-72) there is a short account 
given of my views of the zoological position of the Kagu; but no details are added as 
that paper was merely intended to be an introduction to one more exhaustive and that 
should contain the results of much more labour and thought. More recently, in my 
memoir “On the Shoulder-girdle and Sternum” (Ray Soc. 1868, pp. 158-160), I have 
spoken of the relationships of this bird; but those remarks merely have reference to 
what is indicated by the parts of the skeleton which are there treated of. With regard 
to the nomenclature of those parts (namely, the breast-bone and shoulder-bones), re- 
ference to the memoir itself will show that there is some change of the terms used in 
my older papers on these subjects; this has become a necessity on account of the 
additional light obtained from severer research. Here, also, I must crave the liberty of 
modifying terms used by me in time past, and also of dropping some that seem now to 
be inaccurate, and of coining new words in cases of absolute need. The splint-bones 
that invest the face have cost me the most trouble in researches into the morphology 
of the skull; for I have strained after an harmonious view of the facial bones in the 
whole vertebrate subkingdom, and the Bird has always appeared to me to be the very 
class-type that ought to show the transition from the Ovipara to the Mammal. Un- 
doubtedly it does; but it presents the greatest difficulties to the anatomical student— 
the process of ossification being so intense in degree, and so varied in relation to time 
in this Class.) Hence the morphological observer has to lie in wait for the various 
osseous centres, never knowing when they may appear in the different groups, and 
being equally uncertain when they shall lose their individuality. The Bird’s face has 
always appeared to me to be what one might suppose that of a Fish to become, if that 
low type were to undergo a series of metamorphic changes; it is this great unlikeness of 
the Bird’s face to that of a Reptile or a Mammal which makes its morphology so difficult 
of interpretation. When I first lighted upon an additional bony element (a bone 
which I at once saw must answer to the outer alveolar plate of the mammalian max- 
illary), my difficulties with regard to the Bird’s upper jaw were only becoming greater 
instead of receiving their ultimate elucidation. Well knowing from embryological 
researches into the structure of the skull and face in the large Serpents that their so- 
