Mr. W. K. Parker on the Osteology of Baleniceps rex. 445 
TETRAGONOPTERUS EZNEUS, 
D.11. A. 26. V.8. L. lat. 35. L. transv. 7/6. 
The height of the body is contained three times or three and a half 
times in the total length, and the length of the head four and four- 
fifth times. The interorbital space is convex, and its width more 
than the diameter of the eye, which equals nearly the extent of the 
snout. Uniform bronze-coloured, with a brownish spot at the root of 
the caudal. 
Hab. Fresh waters of Oaxaca (Mexico). 
MOEN 5 oo 5 es be nn 3 oes Mae hemes eae 
mipipnt of the body.’ 66.06 vase cscesasene | ae 
Been ot the head... <s«s vs: ie cane oe 0 8} 
Beeeertct OF CNO-CVG, 52s otc ens teen SS ES - 
June 26, 1860.—E. W. H. Holdsworth, Esq., F.L.S., in the Chair. 
Asstract or Notes ON THE OsTEOLOGY OF BALZNICEPS 
REx. By W. K. Parker, Mens. Micr. Soc.* 
The first view of the living Baleniceps at once suggests the idea 
of the Boatbill (Cancroma), the Heron (Ardea), and the Adjutant 
(Leptoptilus). Other large-headed birds occur to the mind on a 
longer observation ; for one instinctively thinks of the Pelican (Pele- 
canus), the Toucan (Ramphastos), the Hornbill (Buceros), and the 
Podargus, although these birds belong to distinct and very remotely 
related groups. Nor does the internal structure of this noble but 
strange and weird-looking bird contradict the first external impres- 
sions; for the very unusual size of the head, and its great strength, 
require certain modifications of a teleological character, such as 
occur in the large-jawed species of other widely separated groups. 
The difference in the structure of the skeleton between the Baleni- 
ceps and its small New World relative, the Cancroma cochlearia, is 
greatly exaggerated by the necessary modification of the bones in 
the giant species, by their thickness, and by the size of the ridges 
and out-standing processes for muscular attachment; but the two 
- birds are, nevertheless, near allies. In the skull, especially, is this 
difference exhibited; and any large bird may differ osteologically 
from its small relations from this cause, much more than from any 
necessary specific or generic distinction of character. 
Again, any peculiarity of habit in an aberrant species, or genus, 
will make, as it were, large demands upon the structure of those parts 
or organs which are subservient to this (as it regards the group or 
family) eccentric mode of life. The Secretary-bird (Serpentarius) 
amongst the Vultures, the Spoonbill (Platalea) and the Oyster- 
catcher (Tematopus), the Pelican and the Scissors-bill (Rhynchops), 
each form so different from its relations, are familiar instances of 
this law. 
* This paper will be printed entire in the ‘ Transactions,’ accompanied by illus- 
trative plates. 
