MR. W. K. PARKER ON THE OSTEOLOGY OF BALANICEPS REX. 331 
the two posterior pieces. In the second dorsal the two hinder processes are rather 
nearer the anterior end of the centrum, and are now evidently only one bifurcating 
piece. In the third dorsal this piece is losing its lateral processes ; in the next three 
vertebra they have become simple and further backwards in position, whilst in the last 
joint, that which articulates with the sacrum, this mesial process has vanished. 
Retaining the familiar and valuable term ‘ parapophysis’ for all these processes, we 
would distinguish the most marked varieties by a prefix, which should indicate their 
place and function. Thus Pre-parapophysis will indicate in birds that process which is 
anchylosed above to the rudimentary rib, and which sends down a spur of bone below 
to form half the carotid canal; in Ophidia it may be seen as a short and blunt spur 
beneath the articular diapophysis. i 
The posterior outstanding processes below the lower cervical centrums in the Penguin, 
Cormorant, and Fowl, and the pair of processes which form an open hemal canal in 
the true Ophidians, and a closed canal in the Blind-worm, may be called Post-parapo- 
physes. 
The single inferior median process, so common in the centrums of the Vertebrata, 
can take on the prefix hypo ; then, instead of hypapophysis, we shall have hypo-parapo- 
physis. ‘The caudal hemal spine in the little Anguis fragilis, and in those fishes where 
there is no sign of its being anything but an exogenous growth from the down-bent 
parapophyses, may be termed a meta-parapophysis. Lastly, where this lower trans- 
verse process arises from near the middle of the side of the centrum, as in many 
osseous fishes, no prefix need be used: it is simply a parapophysis. 
Professor Huxley shows that the ribs themselves, and the ‘ chevron bones’ of the 
caudal vertebrze of many of the higher Vertebrata, are all developments of the ‘ centrum,’ 
but having a distinct ossific centre’. 
Several of the middle cervical vertebre have perfectly bony carotid canals in the 
following genera—viz. Baleniceps, Cancroma, Ardea, Botaurus, Mycteria (M. australis), 
Pelecanus, Sula, and Picus; the number is variable in skeletons of the same species, 
being greatest in old birds. However, asa rule in the class of birds, the mesial part of 
this canal is completed by interosseous membrane. 
Dorsal Vertebre and Ribs. (Pl. LXVI. figs. 1 & 7.) 
The four true dorsal vertebre of the Baleniceps are quite distinct from each other 
and from the sacrum. In the Pelican, and in one of the Humming-birds, the Mango 
Colibris (Trochilus colibris), the last two dorsals have entirely coalesced with the 
sacrum ; that they are dorsal and not sacral vertebre is proved by their anterior posi- 
tion with regard to the iliac bones, the true sacrals being over-canopied by these large 
* pleurapophyses.’ 
The neural spine of the first dorsal is the longest, being seven-eighths of an inch in 
? Croon. Lect., pp. 48 and 71. 
