Only the body, after skinning, of the species, was brought home by Mr. Darwin. The skeleton of this species does not differ in anything but admeasurements from that of _Pterotochos Tarnii_; the pelvis, however, being so much damaged in that species, that I was not able to make many notes upon it, I shall give a description of that part in the present one. Pelvis of moderate size; the ossa pubis and ischium much expanded, and elongated posteriorly, and placed nearly perpendicular to the plane of the ilium, ischiatic foramina large; two large processes arise on the ilium on each side of the junction of the caudal vertebræ for the attachment of the levator muscles of the tail. lines Length of pelvis 14 Breadth posteriorly 8½ anteriorly 4 Length of sternum 9½ Breadth of ditto 7 In the narrowest part 5½ Depth of keel 2½ Length of coracoids 7½ Breadth of scapula in the widest part 1 No. of cervical vertebræ, wanting. dorsal ditto, wanting. sacral ditto 9 caudal ditto, wanting. Remarks:—Both this and the foregoing bird are most curious; it is difficult to say in what order they ought to be placed, the external form being equally ambiguous with the internal structure. The digestive organs nearly agree with that of many insessorial birds; the pelvis also approaches nearly in form to that of the thrush; the sternum, however, differs altogether from any form found in that order, and is precisely that of a _Picus_. The coracoids are lengthened; the os furcatum is furnished with only a slight process where it approaches the sternum, in which particulars, also in the form of the ribs, it agrees with the _Picidæ_. Having found the internal structure so curious, and so contrary to what I expected, I was led to examine the external more minutely than I had before done. The same form of claw is found in several species among the cuckoos, in the genus _Pelophilus_, for instance; the two outer toes are zygodactyle, being united together as far as the first joint; the bill, at first sight, might be taken for that of a gallinaceous bird; but in searching among the order _Scansores_, for some resemblance, I find the same structure in several of the cuckoo family, with the exception of the nostrils being nearer to the apex of the bill in _Pterotochos_. The Australian genus _Menura_ is, probably, allied to this, but differs in the structure of the nostrils.[32] SYNALLAXIS MALUROIDES. _D’Orb._ (Female.)