PHYLOGENY OF TIIF. PAL.^OGNATILE AND NEOGNATH.E. 257 



My only point concerns the moderator band first described in Casuarins h) 

 RoUestou. It seems to liave been taken for granted by subsequent writers that this 

 was always present, if not in all the Palwognathce, at least in the Casuariidm. 



I have only succeeded in finding it once, and in the heart of a Casuarius casuarius 

 salvadorii, though I have examined specimens of C. unapi)endic%ilntus, C. casuarius 

 beccarii, C. casuarius violicoUis, 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 " chordae 

 tendinese " extending from the outer surface of the auriculo-ventricular valve to the 

 anterior ventricular wall, recalling the similar structures described and figui-ed by 

 Lankester [45] in the heart of Ornithorhynclins. In Bhea and Droma?us only one of 

 these threads was present. I have, however, only had the opportunity of examining 

 one JJrovueus for this purpose. 



The septal half of the valve in Casuarius is thick and fleshy. In Dromceus it is 

 relatively somewhat larger, and, in the (uily adult heart which I have had an 

 opportunity of examining, differs from Casuarius 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. 8 b) 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 Dromaics, 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 thu 

 valve, and from it to the anterior wall of the ventricle. 



Trabeculse carnese were well developed both in Bhea and Dromceus. 



Carotids. 

 All the Palceognathoi, save Apterijx, have normally two carotids. Occasionally, in 

 Rhea, the left only persists. In Apteryx 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 PaUeognathce, as in the Neognatha\ 

 is divisible into a copro-, uro-, and proctodceum, as defined by Dr. Gadow [24]. 



In Casuarius, Rhea, and Apteryx the coprodisum passes g radually into the rectum, 

 but in Struthio and some Neognafhce the coprodceum is preceded by an additional 



