1889.] MR. W. K. PARKER ON STEATORNIS CARIPENSIS. 175 
seen how Bucerine the palate is. This isomorphism, however, has 
to be taken for what it is worth; it is very limited, and in the great 
Cuculine group (Coccygomorphze) we everywhere meet with charac- 
ters in one Family that correspond in some degree with those in 
another, where everything else is very unlike. This is to be noted in 
the contrast seen between the dorsal vertebra of the Bucerotide and 
those of Steatornis. In the former they are cylindroidal, and very 
broad, widened, and flat below; those of the latter runintoa mere keel. 
Also, in the Bucerotide the spines in the dorsals ferm a feeble saddle- 
backed series, having a concave general outline ; in Steatornis they 
form a strong straight series, and the interspaces between the spines 
are very small. In a New-World Kingfisher (Ceryle aleyon) the 
hinder dorsal centra make a great approach to those of Steatornis, 
without, however, being opisthoccelous. 
The peculiarity just referred to in the ribs is their great breadth 
above, their narrowness below, and the low position of the uncinate 
processes (p.u.). The second pair are the widest ; they are 6 millim. 
across for some distance below the tuberculum, and only 3 millim. 
near the lower condyle ; the processus uncinatus is only 11°5 millim. 
at its base, above that, the condyle is 13 millim. long, and has an 
average breadth of 2°5 millim. The Ist sacral has a pair of ribs 
which have a sternal piece, imperfect, but 17 millim. long. The Ist 
dorsal sternal piece is 14 millim., the last 28 millim. long; they 
have an average width of 2 millim. The sacral vertebre and the 
whole pelvis (Plate XIX. figs. 2, 3, and Plate XX. fig. 6) are very 
much like those of Ceryle aleyon,—the Kingfisher whose dorsals show 
a tendency to the opisthoccelous character, and have deep, concave- 
sided dorsal centra, with long, basally-dilated, inferior spines. As 
in that bird and the Hornbills the sacrum is completely ankylosed 
to the iliac bones, even in the young bird of the first year. This 
perfect union of the lateral with the median elements of the pelvis 
is seen in the Common Cuckoo (Cuculus canorus) in young birds of 
the first summer, but it is not seen in Coccyzus nor in Saurothera, 
even in old birds, so that this character must be a thing dependent 
upon conditions, being so variable in nearly related types. The most 
remarkable thing of all, however, is this, namely, that whilst these 
parts are completely ankylosed in the young Cuckoo, in the hinder 
half of the sacrum of an old bird the sutures are quite distinct. This 
is a phenomenon of the same nature as the re-segmentation in the 
adult of the last sacral of the young bird to increase the number of 
the free caudal vertebra, a very common thing in the higher birds’. 
The first three sacrals are not yet ankylosed by their centra in 
the youngest specimen, and the Ist only is partly distinct in an 
1 T cannot leave this part of my description without remarking that this 
must be part of some general law with regard to the evolution of the higher 
kinds of birds, Intense ossification is the thing we are most familiar with in 
the osteology of birds, as compared with other Vertebrata. And yet the birds 
that are manifestly most archaic are often most intensely ossified: thus, to take 
a single fact, an archaic bird is often, not always, desmognathous, whilst a 
more specialized, newer, and nobler bird of the same family will be schizo- 
gnathous. 
