r 501 ] 



XVII. On the Osteology of the Kagu (Rhinochetus jubatus). 

 By W. K. Parkek, F.B.S., F.Z.S. 



Head January 9th, 1868. 



[Plates XCI., XCII.J 



In the Proceedings of this Society for 1864 (pp. 70-72) there is a short accoimt 

 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 ray 

 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 hai'monious view of the facial bones in the 

 whole vertebrate subkingdom, and the Bird has always appeared to me to be the sery 

 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 iincertain 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- 



