182 MR. W. K. PARKER ON STEATORNIS CARIPENSIS. [Apr. 2, 
Steatornis; and the shape and strength of its leg-bones are in great 
contrast to what we see in such Fowl-like Coccygomorphez as the 
Musophagidee and the Ground-Cuckoos. 
The femur (f.) of Steatornis is, perhaps, the straightest to be 
seen in the Class; the breadth is 8°3 millim. above and below, and 
it narrows to a diameter of 3°5 millim. in the middle of its shaft. 
The condyloid ledge for the feeble fibula (fb.) is not well-marked ; 
that bone is a little above half the length of the ¢idia, which latter 
bone is as straight and primordial as the femur; it would seem as if 
these bones had not altered in shape since the middle of incubation. 
The breadth of the head of the tibia (¢.) is 9 millim., across its tarsal 
base 8 millim., whilst the middle of the shaft is only 3 millim. 
The cnemial ridges are very rudimentary, and the ridge outside 
for the fibula (/%.) only reaches 15 millim. downwards. 
A thin delicate tendon-bridge exists in front of the base of the 
tibia below (Plate XX. fig. 4); but there is no special depression 
between the astragalar and calcaneal regions of the condyle, for the 
intercondyloid knob on the distal tarsal (or head of the shank) is 
nearly obsolete (Plate XX. fig. 3). The inner part of the condyle 
is formed by the astragalus, and the outer by the os calcis; there 
is a rudiment of the intermedium between them; the centrale, or 
“naviculare” (nv.), is seen as a cartilaginous, curved wedge behind 
the joint. The tarsal outgrowth behind the head of the shank to 
form a tendon-canal for the plantar tendons (Plate XX. figs. 3, 5) is 
open. This part is closed in, and forms one canal in Ceryle aleyon ; 
in the Martin (Chelidon urbica), as in all the Coracomorphe, there 
are five canals in the compound mass; in the Swift (Cypselus apus) 
there is an unusual thing—a little bridge in front of the distal tarsal ; 
but the two ridges behind are not united". 
There is a notable peculiarity in the structure of the znter-tarsal 
joint. The condyloid trochlea formed by the astragalus is large and 
perfect, and rolls in a well-formed concavity on the inner side of the 
great distal tarsal. But the calcaneal part of the double trochlea is 
feeble (Plate XX. figs. 3-5) and the outer part of the facet on the 
lower tarsal is almost flat’. 
The tarso-metatarsus shows the signs of division into three main 
metatarsals, both above and below, 2nd to 4th (Plate XIX. figs. 4, 5). 
The free distal piece that carries the “‘ ballux”’ (m¢.¢’.) is 5-5 millim. 
long. 
On the outer side of the head of this small shank the 5th meta- 
tarsal (mt.t. 5) can be seen as a club-shaped rudiment, fused with 
1 The classification of birds by the palate is very useful as a help to other 
methods, everything else being taken into account. Nowhere does it show its 
value more than in the Coracomorphe ; they are all “ Hgithognathous” ; but 
the Aigithognathe and the Coracomcrphe are not equal groups—the former 
is too large for accurate superposition on the latter; the Swifts (Cypselidz) are 
Egithognathx, but they are not Coracomorphe. 
2 This obliquity reminds one of that in the free astragalus itself in the Mega- 
therium, as compared with the same bone in the Horse, the latter having the 
condyle in two nearly equal, oblique semicircular elevations, whilst in the 
former the two convexities are extremely unequal. 
