Page 196. 
326 ON THE ANATOMY OF CHAUNA DERBIANA. 
forwards as its junction with the pubis, being here slightly overlapped 
by the semitendinosus. The fibres converge towards the knee; and 
the deep portion of the muscle blends in its course with the vastus 
externus, together with which it continues forward to become part of 
the broad thin tendon which covers the knee and is inserted in the 
front of the tibia-head, the patella being situated in it, together with 
the long, slender, and flat tendon of the ambiens muscle, which is 
situated below it, running obliquely from inside and above, outwards 
and downwards. In many birds this muscle does not extend below 
the level of the femur, but ends inferiorly by blending with the vastus 
externus; and consequently, where such is the case, it evidently 
cannot, as it does otherwise, cover any of the flexors of the leg.” 
Whether this postacetabular portion of the tensor fascie is present or 
absent can be found by referring to the Table (p. 329). There are 
not many birds in which it is very small. 
As the Anserine affinities of the Screamers are being discussed, it 
ought to be mentioned that in all the former the great pectoral flexor 
of the wing is peculiarly elongate, and extends upwards above the 
symphysis furcule, with its fellow forming a medium raphe as an 
anterior continuation of the carina sterni. The only other birds in 
which this occurs are the Penguins. In the- Screamers the great 
pectoral flexor is not large, and does not extend upwards above the 
middle of the furcula. 
In the Anseres the extensor pectoral (second pectoral) is always 
very long and broad, reaching the lower end of the sternum. In 
Chauna it does not extend nearly to the posterior margin of the 
sternum, and it is not bulky. 
Again, the muscles of the Anseres are always intensely dark in 
colour, whilst in the Screamer they are quite pale. In this respect 
the two groups differ in the same way as do the Seals and the Sirenia 
among Mammals. 
Osseous System.—The skull, being that portion of the skeleton 
which is least permeated with air, will receive the greatest attention 
on the present occasion. With reference to it Prof. Parker remarks*, 
‘** All the skull and face, except at its two ends, conforms to the 
lamellirostral type.” Prof. Huxley also places Palamedea in his group 
“Chenomorphe,” among the several features characterizing those 
birds being that “the lachrymal region of the skull is remarkably 
long.” That such is not the case in Chawna, Prof. Parker has 
remarked in his article “ Birds” in the Encyclopedia Britannica ft. 
It may be well before proceeding further to inquire more fully 
* “Proceedings of the Zoological Society,” 1863, p. 514. 
+ “Enc. Brit.,” 8th edit., vol. iii, p. 712. 
