196 NATURAL HISTORY OF BIRDS. 



ORDER XI. OPISTHOCOMI. 



The extraordinary bird, Opisthocomus cristatus, which is the sole species of the 

 family OPISTHOCOMID^E, has been for a long time a complete puzzle to naturalists, as 

 it seemed to combine within itself characters of so many groups, that it was almost 

 impossible to decide where it should be referred, and therefore by various writers it 

 has been assigned from one family to another, until there appeared to be no resting- 

 place for it anywhere. Of late years, however, several entire specimens having been 

 obtained preserved in spirits, its myological and osteological structures have been 

 thoroughly studied by several fully competent naturalists, and the general verdict is, 

 that, while allied to several, it belongs to none of the other groups of birds, but consti- 

 tutes a distinct order and family, of which it is the only known representative. Out- 

 wardly it is not an ungraceful looking bird ; having the upper part of the body dark 

 brown, with a white streak upon the feathers of the hind part of the neck ; head cov- 

 ered with a long loose crest, and a bare skin around the eye. Two white bars cross 

 the wing, formed of the tips of the wing coverts. Throat and breast deep fawn, belly 

 and crissum rufous. Tail long and colored like the back, the feathers tipped with 

 brownish white. Its pterylosis, or feather-tracts, presents, among others, some of the 

 following characteristics : There are no lateral neck-spaces. The inferior tract 

 beginning at the bottom of the neck runs in two broad bands to the keel of the ster- 

 num, where they narrow, and pass on growing gradually narrower to the anus, 

 terminating in only two feathers in width. The dorsal tract divides between the 

 shoulders into two limbs, and becomes broader from the caudal pit onwards, enclosing 

 the oil gland, which has a circlet of feathers at the tip. The skeleton has many pecu- 

 liarities, among which the following may be mentioned : The antepenultimate dorsal 

 vertebra is free ; the six or seven hindermost cervical vei'tebras only have very weak 

 median inferior crests, and the inferior faces of the centra of the dorsal vertebra are 

 flattened and without crests. The sternum is unique, the lateral edges are nearly 

 parallel for two thirds its length, then diverge so that it is wider posteriorly than an- 

 teriorly. The posterior edge has two notches on either side, the outer pair possibly 

 foramina, the inner pair deeper, but not extending a sixth of the sternum's length. 

 The keel is very small and cut away in front, and has a prominent tubercle at its 

 distal extremity (carina sterni), with a somewhat flattened surface, and separating the 

 fibres of the pectoral muscles at this point. This expansion of the sternum is covered 

 by the bare skin, and can be readily seen when the bird is picked. The sternal ribs 

 are attached to the anterior half of the lateral margin. The coracoids are anchylosed 

 with the clavicles ; the f urcula is very short, and it is so completely anchylosed with 

 the coracoids as to leave no trace of their distinctness ; and inferiorly the straight 

 hypocleidium is completely anchylosed with the manubrium. The pelvis is without 

 any ilio-pectineal process, and the ilio-sacral fossas are completely roofed by bone. 

 The skull has no basipterygoid processes ; the vomer is slender and compressed, and 

 the maxillo-palatines are ill-developed. The transverse hinge of the rostrum lies 

 behind the lachrymals, which are coalesced with the nasals and form part of the 

 rostrum. The crop is enormous, occupying all the upper part of the chest, and by its 

 great size, distorts the furcula and sternum, and entirely conceals the superior and 

 anterior halves of the pectoral muscles, and, when it is removed, the upper halves of 

 the pectorals are seen to form a deep cavity in which the crop is placed. The above 



