2 I 
Osteological Studies of the Subfamily Ardeince. 
and my only regret is that I have not at this moment the proper 
material to investigate whether or no a like method of develop¬ 
ment goes on in the young of the Herons. 
As for the distal extremity of this bone, it also has received 
no little attention generally, but in particular the young of our 
present subject has been ably investigated at the hands of Pro¬ 
fessor Morse. 
It was through his studies of the tibia and tarsus of immature 
individuals of various species of Ardca that this distinguished 
zoologist was principally enabled to demonstrate the presence of 
the intermedium in the class birds. Professor Morse’s researches 
have proven, I think, beyond doubt, that the “ ascending process 
of the astragalus” of Huxley agrees with the “pretibial” of 
Wyman. Further, this segment ossifies from a separate centre of 
ossification, and as such constitutes in the avian tarsus a third 
bone of the proximal row, which corresponds with the intermedium 
of the Reptilia as described by Gegenbaur. No marked suspicion 
exists of the presence of any such bone in the adult, in any of the 
Ardeince , it having been completely absorbed by the tibia, and 
every vestige of its original limits obliterated. 
The fibula of the Great Blue Heron is a very much aborted 
bone, both in comparison with many other birds and with the size 
of its own tibia (Figs. 19 and 20). 
The upper surface of its distal end is devoted entirely to the 
facet for articulation with the condyle of the femur. Below this 
the bone is compressed from side to side, and produced from be¬ 
fore, backwards. Then rapidly contracting it presents a rough¬ 
ened surface intended for ligamentous attachment to the fibular 
ridge of the tibia. Near this we see the tubercle for the insertion 
of the tendon of the biceps. The remaining length of the fibula 
becomes almost needle-like in its dimensions, and makes no osseous 
connection with the tibia whatever, passing but little below the 
upper third -of its shaft, which when the bone is removed shows 
no evidence of its contact, more than the roughness of the fibular 
ridge. 
Ardea candidissima has a fibula that agrees in all respects 
with the one I have described for the Great Blue Heron. I11 
Nvcticorax it differs in one important particular, and this is, that 
—- 
after passing its articulation with the fibular ridge of the tibia, its 
almost thread-like dimensions are carried well below the middle 
