1909.] 



STRUCTURE OP THE LESSER ANTEATER, 



695 



auriculo-ventricular valve, which is incompletely shown in the 

 same text-figure (text-fig. 222), has a very complicated series of 

 papillary muscles, as is better shown in text-fig. 223. As in the 

 Great Anteater*, the tricuspid valve is attached at the extreme 

 left directly to the septal wall of the ventricle ; there is here no 

 development of a papillary muscle or muscles. The great or 

 anterior papillary muscle ("a" in Sir E. Ray Lankester's figures) 

 is partly divided into two, but not so markedly as he figures it in 

 the genus 2Iyrmecophaga. From the collar of the valve exactly 

 opposite to the anterior papillary muscle arise two muscles which 

 appear to be represented but are not lettered in the drawing of 

 Lankester already referred to. These are fixed to the free wall 

 of the ventricle. The right-hand one of them, which is the 



Text-fig. 223. 



The same heart with the moderator band removed to show more plainly the 

 structure of the right auriculo-ventricular valve. 



The left (great) anterior papillaiy muscle, h^. The right (lesser) papillary 

 muscle, h. Muscle arising from the free wall of the ventricle and attached 

 (the other cut end is also shown) to the actual collar of the annular valve. 



smaller, is nevertheless the more conspicuous, since it is attached 

 farther towards the apex of the heart upon the free wall of the 

 ventricle. The arrangement of these muscles is very suggestive 

 of ^he muscles lettered "m'*'and " 7i " in Lankester's figure of 

 the heart of Ornithorhynchvs. 



The right anterior papillaiy muscle in Tmnandua is a very 

 slender muscle attached to the free wall of the ventricle. To 

 this series may be also referred a double muscle situated more to 

 the right, and also arising from the free wall of this ventricle. 



* Cf. Lankestei', loc. cit. fig. cit. " e." 



