720 



MB. F. B, BEDDARD ON THE 



[Dec. 4, 



ance as diagnostic of the Monotreme heart than the fact of the 

 greater muscularity of the valve. 



This conclusion was obviously warranted by the facts discovered 

 by Prof. Lankester ; but the heart of Ornithorhynchus is more 

 variable, apparently, as regards this valve than would be inferred 



Fig. 2. 



*' 



Testis and vas deferens of Ornithorhynchus. 



t, remains of testis. 

 s, sac in which it is enclosed. 

 m, membrane attaching this sac to vas deferens {Sp). 

 n, membrane attaching sperm-duct to body-wa 11. 



from Prof. Lankester's paper. The first of the two hearts which 

 I dissected was, at first sight, almost exactly like that figured by 

 Prof. Lankester in fig. 14 of plate xl. of his memoir. The muscle 

 " h " was single and there was a small membranous septal flap 



