MR. W. K. PARKER ON THE OSTEOLOGY OF BAL^NICEPS REX. 343 



nating class of Vertebrates, is very great, but must be resisted ; yet the foregoing table, 

 although purposely exceedingly limited, might serve as prologue for a discourse of any 

 length'. 



The main bones of the leg in Balseniceps are nearly exactly one-third longer than those 

 of the Grey Heron, and one-third thicker. They have also very much the same struc- 

 ture. There is nothing particular to remark in the very straight cylindrical os femoris 

 (PI. LXVI. tig. 1/rft), with its roundish head, short neck, and its broad and externally 

 rugose great trochanter — the upper facet of which is coated with articular cartilage, to 

 glide upon the supra-acetabular facet of the ilium. The articular ends of the ' tibia ' 

 (PI. LXVI. figs. \,8 &9tb) are well developed — the two upper facets for the condyles of 

 the femur being very flat as in most birds ; and the ecto-, ento-, and epicnemial ridges are 

 as well developed as in the Heron. This part of the tibia has a separate epiphysis in 

 the young Emeu. There is a fibular ridge outside for the fibula, which bone is thick 

 at the top where it glides under the fibular condyloid process outside the lower external 

 condyle of the femur. The lower part of the fibula (PI. LXVI. fig. Ifb) is styloid, and 

 this bone is short in the Balaeniceps, being less than three inches long, whereas it is nearly 

 an inch longer in the Heron, and nine inches in the Adjutant. The sigmoid curve at the 

 lower part of the tibia is very slight, as in the Heron — this bone being straighter in the 

 Ardea than in the Ciconia. The large inferior trochlea of the tibia (PI. LXVI. 

 figs. 8 & 9 <6) is well developed, as is the osseous bridge in front and above it, and the 

 internal and external tubercles on its sides. These parts are larger in proportion in the 

 Baleeniceps than in the Heron. This inferior or distal end of the tibia is developed from 

 a distinct osseous centre in young birds, which piece forms all the articular part, and 

 sends upwards a wedge-shaped process in front — the seat of the ossification which makes 

 the large, wide, oblique tendon-bridge. Below this bridge the bone is deeply scooped, 

 and the concavity between the condyloid margins of the trochlea is very considerable. 

 Query — Is this lower articular portion of the tibia an epiphysis of the tibia itself, or is it 

 the homologue of the mammalian astragalus ? There is no ' sesamoid ' os calcis in the 

 Balseniceps, in which it agrees with the Herons and Storks. 



The tarso-metatarse of Balseniceps (PI. LXVI. figs. 1, 8, 9, 10 & Mtmt) has its arti- 

 cular extremities more strongly developed than in the Heron, — its length and thickness 

 still retaining the same relative size as the tibia, femur, and the bones of the wing. 

 This bone is one-third longer than the same bone in the Heron, and one-third thicker 

 in its shaft; but the ecto- and ento-condyloid cavities and their margins are more 

 strongly developed. The concavity also below and in front of the head of this bone is 

 unusually deep ; but the intercondyloid tuberosity is not better developed than in the 

 Boat-bill and the Herons, being very inferior to the same part in the Adjutant. In the 



' In the works of Sir C. Bell, Dr. R. Grant, and Professors Owen and Rymer Jones, the reader wUl find this 

 subject treated of as it should be. 



3 b2 



