OCR Text |
Show 1889.] MR. W. K. PARKER ON STEATORNIS CARIPENSIS. 179 length of the ulna, whilst the manus is more than three and a half times as long as the humerus. In Steatornis, on the contrary, the humerus (h.) is seven eighths the length of the manus, whilst the former is only two thirds the length of the ulna, and the manus less than four fifths. Caprimulgus is intermediate between these two extremes ; its wing-regions increase in size in a regular manner (from above downwards) ; it is a sub-typical " Macrochire." Buceros is the most remarkable in one respect; its manus is only four-sevenths the length of its ulna. In the two good instances of birds with a light buoyant flight, the White Owl and the White Gull, the greater length of the ulna as compared with the humerus is similar in both birds; but the Gull has its ulna and manus of the same length, whereas in the Owl the latter is only six sevenths the length of the ulna or cubitus. All these birds have to be considered separately in their various modifications, and no inference as to their genesis made rashly from some one or more similarities in their adapted structures. I might have included Podargus humeralis amongst the birds whose wings were measured; but it gives me little help in seeking to find the affinities of Steatornis. Podargus appears to me to be more allied to Eurystomus; its sternum and pelvis differ greatly from those of this Neotropical bird, and its wings are more normal in the relative length of the three regions. Thus the humerus in Podaryus is 74 millim. long, the ulna 88 millim., and the manus 68 millim. The relations of Podargus must be sought for in the Australian Region and the Eastern Notogaea, generally; those of Steatornis in the Neotropical Region ; whilst the true Goatsuckers, or Caprimulgidae, must find their ancestors where they can. I cannot see m y way to " father them" on either Steatornis or Podargus; yet both of these types may possibly be not unlike the birds that, during time, have been specialized into the true Goatsuckers. I can only find a pneumatic foramen in the humerus (h.); that bone is quite normal; its upper crest for the insertion of the great pectoral muscle is large, and the dilatation below is hooked inwards, hollowed out and perforated to let in the air. The distal condyle is well developed, and there is above it, on the flexor side, a semi-oval hollow for the origin of the flexor muscles1. The long, slender, gently sigmoid radius (r.) and arcuate ulna (u.) are quite normal; the latter is marked very slightly for the secondary quills. The radiale and the ulnare are also well developed and perfectly normal; I see no " sesamoids " attached to them. The top of the manus has the large 2nd distal carpal (d.c.2) over the large middle metacarpal, the lesser 3rd distal carpal (d.c.*) on the outer side of the top, and the 1st distal carpal (Plate X X . fig. 2, d.c.1) is seen as a knob looking towards the 1st metacarpal, but ankylosed to the 2nd. 1 Mr. Frederic A. Lucas finds an "os humero-capsulare" in this bird (see Plate X X . fig. 1, o.h.c). |