642 MR. w. A. FORBES ON THE [May 17, 



special long flexor, the great size of their feet having heen developed 

 in accordance with their peculiar habits. 



In the anterior extremity the second pectoral arises from nearly 

 the whole length of the sternum ; in all three genera the third pec- 

 toral is wanting. The expansor secundariorum is strong and 

 T-shaped, as in all Balline and many Pluvialine birds. In Parra 

 jacana (as in Hydrophasianus, according to Garrod) there is a dis- 

 tinct biceps slip to the patagium, as in all the Rallidoe, the Chara- 

 driidse, Gruidse, and many other Pluvialine birds. In Metopidius 

 africanus it is apparently absent, the absence being probably corre- 

 lated with the pecuhar expanded form of the radius (to be hereafter 

 described). 



In the wing-membrane the tensor patagii brevis presents a pecu- 

 liar arrangement, t)ie tendon being completely divided into two por- 

 tions — an inner, more slender, and an outer, stronger one. The 

 former runs on to the fibrous tissue near the superficial origin of the 

 extensor metacarpi radiulis longior, and there stops ; the latter con- 

 tinues over this last muscle to the ulnar side of the arm, where it is 

 lost in the fibrous covering-tissue adjacent. Before crossing, how- 

 ever, it sends off a short, special wristward slip to the superficial 

 tendon of origin of the metacarpal extensor, as in many other groups 

 of birds. There is also a thin fibrous expansion given off just before 

 this to the tendon of the tensor patagii longiis, and the tissue of the 

 patagium generally, as in many Pluvialine birds '. This splitting 

 up of the tensor patagii brevis tendon into two distinct slips, the ex- 

 ternal one in turn giving off a special wristward slip, occurs in many 

 Pluvialine birds {e.g. in Nnmenius arquatiis, Totanus calidris. Ma- 

 chetes pugnax, Himantopus nigricolHs, Thinocorus, and Attagis), but 

 never in the Eails, where the tendon is always much more simple, 

 not being divided into two separate parts, or giving off a wristward 

 slip. In fact, in most Rallidae it runs quite simply, as a narrow 

 straight tendon, onto the origin of the extensor metacarpi muscle, 

 and there stops. 



The trachea is provided with the usual pair of sterno-tracheal 

 muscles; and the lower larynx, which is of simple structure, has also 

 only a single pair of intrinsic muscles. 



Osteology. 



From a consideration of the pterylographic, visceral, and myolo- 

 gical features only of the Parridae, perhaps no very definite conclusion 

 as to their affinities could be drawn. But their osteological cha- 

 racters, in this case, leave no doubt as to their real position. All 

 the skulls of Parridae which I have examined, including those of 

 ParrcB jacana and gyinnostoma, Metopidii indicus, africanus and 

 albinucha, and Hydrophasianus chirurgus, like that of Hydralector 

 cristata figured by Garrod ", are strongly schizorhinal, therein dif- 

 fering completely from that of the Rails, and resembling that of the 



^ In Ht/drophasicmus much, tlie same arraugemeut of the tensor patagii brevis 

 obtains, to judge from a small drawing in Garrod's MS. 

 2 P. Z. S. 1873, p. 34, fig. 5. 



