MR. W. K. PARKER ON THE OSTEOLOGY OF BAL^NICEPS 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, Talec/alla, Perdix, Coturnix, 

 Hemipodius, and PteroclesK In the Common Green Woodpecker, Picus viridis (a solitary, 

 shy, suspicious bird), we find very beautiful tympanic bullas, 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. 



Oshyoides. (Pi. LXVI. fig.2.) 



The Balseniceps 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 (PI. LXVI. 

 fig. 2hh) (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 

 (PI. LXVI. fig. 2 th) 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 

 a half. 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 

 Gallince, viz. Gallus domesticus, Phasianus colchicus, Meleagris yullo-pavo, Tetrao tetrix and T. cupido, Perdix 

 rubra and cinerea, Lagopus scoticus aud Coturnix dactylisonans ; only in the Turkey and Grey Partridge do 

 we find a rudiment of the tympanic, aud that not constantly. It does not exist in Crax globicera. 

 VOL. IV. — PART VII. 2 Y 



