Page 597. 
258 ON THE ANATOMY OF THE PARROTS. 
ambiens muscle did not cross the knee, yet its fleshy belly was well 
differentiated on both sides, its thin tendon being lost over the capsule 
of the joint. In the College of Surgeons’ specimen, however, this 
muscle was entirely absent in the only knee which was in a fit state for 
dissection, the other being much shot. It is only in the genus 
CGidicnemus that I have elsewhere found a similar partial loss of the 
ambiens.* The partial development of this muscle in this particular 
instance shows that the tendency to lose it is not of great antiquity ; 
and it is to be noted that there is no other Parrot with norma: carotids 
in which any trace of an ambiens is to be found. These considera- 
tions suggest, what may perhaps be the case, as is suggested by the 
peculiarities of their geographical distribution, that Agapornis may be 
the representative among the normal-carotid Parrots of the Platycer- 
cine branch from the Arinz, whilst the Stringopine proper (including 
Geopsittacus, Melopsittacus, and Huphema) are more direct continua- 
tions of the main stem, as indicated by the dotted portions of the 
diagrams (Plates [6] LXX. and [7] LXXI.), Stringops itself being the 
nearest living representative of the common ancestor of the whole 
suborder. 
Further, it may be worth while taking a glance at some of the most 
important changes which my classification would necessitate. Taking 
Mr. Sclater’s “Revised List of Vertebrated Animals in the Society’s 
Gardens” as a good representative of current opinion, the Order 
Psrrract is there divided into two families and seven subfamilies, 
thus :— 
Order PSITTACI. 
Family I. StRiINGOPIDA. 
Family II. Psirtacipa. 
Subfamily 1. Cacarurnz. 
ro 2. ARINZ. 
+5 3. PLATYCERCINE. 
+ 4, PsITTAcIna”. 
if 5. LORIINA. 
‘5 6. NESTORINA. 
As far as the major division is concerned, the facts brought 
forward in the present communication suggest a different arrange- 
ment, as shown above, which would approximately distribute these 
subfamilies thus :— 
Family I. Family IT. 
Stringopide. Arine. 
Loriine. Platycercine (in part). 
* Vide “ Proceedings of the Zoological Society,” 1873, p. 640. (Supra, p. 202.) 
