458 Mr. T. C. Eyton on a peculiar Ischiatic Process in Emcivores. 



covered a process attached to the anterior edge of the ischium, 

 which exists throughout the whole order of Erucivores, and is 

 not found in any other group that I am aware of, thus distinctly 

 marking the Cuckoos as an isolated group. The process alluded 

 to is a lengthened and flattened spine attached to the edge of 

 the anterior extremity of the ischium ; it varies much in develop- 

 ment in different genera, being lengthened among the Turacoes 

 and Ground Cuckoos, and least developed, but still apparent, in 

 Chalcites and Cucidus glandarius; but, however rudimentary, 

 it is always present in every genus of Cuckoos that I have 

 examined. 



During Professor Owen's lecture at Leeds on the Fossil Mar- 

 supials of Australia, it struck me as not being unlikely that some 

 form approaching to marsupial structure might be found in the 

 skeletons of birds. On my return home, I examined minutely the 

 i\Ieliphagida3 (thinking that, the metropolis of that family being 

 Australia, some peculiarity might occur among them), but without 

 meeting with anything striking. In mounting a specimen of the 

 skeleton of Turacus gigas, sent to me in spirits, several years ago, 

 from Africa, by 3Ir. Eraser, the process alluded to first struck me. 

 In this bird it is more developed than in any other of the group 

 with which I am accpiainted, except perhaps in Centropus pha- 

 sianellus, projecting from the anterior extremity of the ischium 

 nearly half an inch, and with a nearly obliterated suture between 

 it and that bone, and holding precisely the same position that 

 marsupial bones do among that peculiar class of Mammalia. 

 Although I have, up to the present time, failed to discover a 

 similar structure in birds now classed in other orders, I should 

 not be in the least surprised at doing so, were it not for the 

 mode many genera of Cuckoos adopt in depositing their eggs 

 — some laying them in the nests of other birds, while several 

 females of other species deposit them in a common nest. Little 

 or nothing, however, is known of the nidilication of many genera. 

 The group will now consist of the Cuculidre proper and the Tu- 

 racoes, among which I am still doubtful whether Opisthoconius 

 cristatus ought to be included or not, as I have never seen a 

 skeleton, and, in the lithograph published by Castelnau, ' Expedi- 

 tion dans TAmerique,' the femur crosses the anterior part of the 

 ischium, so as to hide the process if it exists; in other respects, 

 with the exception of the sternum, which is evidently distorted, 

 the whole skeleton resembles the Turacoes. Nor have I yet seen 

 the skeleton of Indicator, which has been usually classed with 

 the Cuckoos. 



