PHYLOGENY OF THE PALZOGNATHA AND NEOGNATH. 257 
My only point concerns the moderator band first described in Casuarius by 
Rolleston. It seems to have been taken for granted by subsequent writers that this 
was always present, if not in all the Palwognathe, at least in the Casuariide. 
I have only succeeded in finding it once, and in the heart of a Caswarius casuarius 
salvadorii, though I have examined specimens of C. wunappendiculatus, C. casuarius 
heccarti, C. casuarius violicollis, C. casuarius sclateri, and Casuarius casuarius. 
In addition to the large papillary muscle binding the right auriculo-ventricular 
valve to the anterior wall of the ventricle, 1 find two or more very slender “ chorde 
tendinee ” extending from the outer surface of the auriculo-ventricular valve to the 
anterior ventricular wall, recalling the similar structures described and figured by 
Lankester [45] in the heart of Ornithorhynchus. In Rhea and Dromeus only one of 
these threads was present. I have, however, only had the opportunity of examining 
one Dromeus for this purpose. 
The septal half of the valve in Caswarius is thick and fleshy. In Dromeus it is 
relatively somewhat larger, and, in the only adult heart which I have had an 
opportunity of examining, differs from Caswartus in that its free ventral or hinder 
border is curved forwards at its insertion towards the floor of the left auricle, 
forming by this means a sort of pocket-like flap on the wall of the inter-ventricular 
septum. 
In Rhea this same arrangement occurs again. In one adult which I dissected 
(fig. 8B) this was remarkably well developed. The valve was very thin, and the 
forward pocket-shaped extension into the anterior end of the ventricle was strongly 
developed and was continued yet further in the form of a narrow slip of muscle 
attached only at its ends. 
In Dromeus, in addition to one or two delicate tendinous threads from the outer 
surface of the auriculo-ventricular valve to the anterior ventricular wall, there were 
numerous fleshy strands of muscle, interlacing one another, running parallel with the 
valve, and from it to the anterior wall of the ventricle. 
Trabecule carne were well developed both in Ahea and Dromeus. 
CaRortiDbs. 
All the Palwognathe, save Apteryx, have normally two carotids. Occasionally, in 
Rhea, the left only persists. In Apterys there is only one carotid, the left. 
CLOACA, BURSA FABRICII, AND URINO-GENITAL SYSTEM. 
a. CLOACA. 
The terminal end of the alimentary canal in the Palwognathe, as inthe Neognathe, 
is divisible into a copro-, wro-, and proctodewm, as defined by Dr. Gadow [24]. 
In Casuarius, Rhea, and Apteryx the coprodeum passes gradually into the rectum, 
but in Struthio and some Meognathe the coprodeum is preceded by an additional 
