112 DICTION AR Y OF BIRDS 



what is elsewhere said in this book (pages 828, 829). It is doubtless a 

 generalized form,^ the survival of a very ancient type, whence several 

 groups may have sprung ; and, whenever the secret it has to tell shall 

 be revealed, a considerable step in the phylogeny of Birds ought to 

 follow. Allusion has also been made to the peculiarities of two other 

 forms placed with the last among the Alectorides — Eurypyga and Ehino- 

 chelus — each being the sole type of a separate Family. It seems that they 

 might be brought with the Gruidae, Psophiidx (Trumpeter), and Aramidgt 

 (Lijipkin) into a group or Suborder Grue.% — which, with the Fulicariae ^ 

 of Nitzsch and Mr. Sclater as another Suborder, would constitute an 

 Order that might continue to bear the old Linnaean name Grallse. It 

 must be borne in mind, however, that some members of both these Sub- 

 orders exhibit many points of resemblance to certain other forms that it 

 is at present necessary to place in different groups — thus some Eallidae 

 to the Gallinae, Grus to Otis, and so forth ; and it is as yet doubtful 

 whether further investigation may not shew the resemblance to be one 

 of affinity, and therefore of taxonomic value, instead of mere analogy, 

 and therefore of no worth in that respect. 



We have next to deal with a group nearly as complicated. The true 

 Gallinse are indeed as well marked a section as any to be found ; but 

 round and near them cluster some forms very troublesome to allocate. 

 The strange Opisthocomus (Hoactzin) is one of these, and what seems to be 

 in some degree its arrested development makes its position almost i;nique.^ 

 It must for the present at least stand alone, the sole occupant of a single 

 Order. Then there are the Hemipodes, which have been raised to 

 equal rank by Huxley as Tur7iicomoiyhai ; but, though no doubt the 

 osteological differences between them and the normal Gallinx, pointed 

 out by him as well as by the late Prof. Parker, are great, they do not seem 

 to be more essential than are found in different members of some other 

 Orders, nor to offer an insuperable objection to their being classed under 

 the designation Gallinae. If this be so there will be no necessity for 

 removing them from that Order, which may then be portioned into three 

 Suborders — -Hemipodii standing somewhat apart, and Aledoropodes and 

 Peristeropodes, which are more nearly allied — the latter comprehending 

 the Megapodiidx (Megapodes) and Cracidae (Curassows), and the former 

 consisting of the normal Gallinse, of which it is difficult to justify the 

 recognition of more than a single Family, though in that two types of 

 structure are discernible. 



The Family of Sand-Grouse, Pteroclidee, is perhaps one of the most 

 instructive in the whole range of Ornithology. In Huxley's words 

 {Proc. Zool. Soc. 1868, p. 303), they are " completely intermediate between 



1 Oariama is the oldest name for the genus, but being a word of "barbarous" 

 origin it was set aside by lUiger and the purists in favour of Diclwlqphus, under 

 which name it is several times mentioned in the present work {cf. Index, 

 page 1066). 



^ This group would contain three families — Rallidw, Heliornithidee (the FlN- 

 FOOTS of Eastern India, Africa and South America) and the Mesitidw of Madagascar 

 — for which an at least approximate place has been found by M. A. Milne-Edwards 

 {Ann. Sc. Nat. ser. 6, vii. No. 6). 



^ Mcsites, just mentioned, presents a case which may, however, be very similar. 



