MR. W. K. PARKER ON THE OSTEOLOGY OF BALANICEPS REX. 317 
research may perhaps be rewarded by the discovery of this interesting element in other 
genera besides Pavo. The genera in which no tympanic has been found are—Gallus, 
Phasianus, Meleagris, Oreophasis, Numida, Tetrao, Lagopus, Talegalla, Perdix, Coturniz, 
Hemipodius, and Pterocles'. In the Common Green Woodpecker, Picus viridis (a solitary, 
shy, suspicious bird), we find very beautiful tympanic bulle, as large in proportion to the 
skull as in ordinary Mammalia. These ear-drums are exceedingly like a pair of small 
cowrie-shells (Trivia), the oblong hourglass-shaped opening looking downwards and a 
little outwards. The posterior end of the opening, which is the narrowest, does not 
reach to the extremity of the bulla, but the wider anterior end is open and receives the 
posterior condyloid process of the os quadratum. The inferior part of the bulla is the 
most dilated, and its edge is the most incurved. This incurving of the edges, as well 
as the smooth surface and oval shape, give the bone its peculiar cowrie-like appearance. 
The upper part of the bulla of the Woodpecker appears to be formed by an ossification 
downwards and forwards from the squamosal and ex-occipital at their point of coales- 
cence ; the lower part would appear to be formed by an ossification forwards of the ex- 
occipital, the inner margin of which becomes anchylosed to the side of the basi-sphe- 
noid. If, however, an opportunity occurs for us to examine this part in an embryo of 
the Woodpecker, we shall very probably find a separate tympanic ossicle of a V-shape ; 
which would come still nearer to the U-shaped tympanic ring of Mammalia than the 
emarginate tympanic of the Pea-hen. The Common Duck has its tympanic cavity 
nearly as well developed as it is in the Woodpecker. 
Os hyoides. (Pl. LXVI. fig. 2.) 
The Balzeniceps has a very small tongue, as is also the case in the Pelecanine birds, so 
that all that exists of the second facial arch is a small triangular basi-hyal (Pl. LXVI. 
fig. 2b h) (not one-third of an inch long, and less in width), and a small subcylindrical 
uro-hyal, about one-sixth of an inch in length. The two pieces of the thyro-hyals 
(Pl. LXVI. fig. 2 ¢h) belong to the third facial or branchial arch (the first post-cranial arch), 
and are moderately developed ; they measure together rather more than three inches and 
ahalf. The proximal piece is thin and scooped on its upper surface ; the distal, smaller 
portion is round, and gradually decreases towards the end, which is tipped with cartilage. 
Professor Goodsir (op. cit. p. 176) says that ‘‘in the second visceral lamina of the 
Bird the auditory columella is developed superiorly, and the feeble anterior horn of the 
hyoid below, while the elements of the suspensory or posterior horn of the hyoid are 
formed in the third visceral lamina.” 
At the end of the second week of incubation, the large proximal piece of the thyro- 
* Since the above was written we have carefully prepared several skulls of each of the following species of 
Galline, viz. Gallus domesticus, Phasianus colchicus, Meleagris gallo-pavo, Tetrao tetriz and T. eupido, Perdix 
rubra and cinerea, Lagopus scoticus and Coturnix dactylisonans; only in the Turkey and Grey Partridge do 
we find a rudiment of the tympanic, and that not constantly. It does not exist in Craw globicera, 
VOL. IV.—PART VII. 2y 
