172 



MB. R. LYDEKKEB OK THE CORACOIUAL [Feb. 14, 



The author's \ lews as to the phj'logeuy of the Eatitse are showu 

 iu the following diagram : — 



OlNORMlb 



P^CHYORN15 



MESC 



MtUS 



DROM 



Rhea 



This Memoir will be published entire in the Society's ' Trans- 

 actions.' 



The following papers were read : — 



1. Note on the Coracoidal Element in Adult Sloths, with 

 Remarks on its Homology. By R. Lydekker, B.A., 

 F.Z.S. 



[Received December 28, 1892.] 



It has been ascertained by the late Professor Parker that the 

 coracoidal element iu the pectoral girdle of the Sloths ossifies inde- 

 pendently from the scapula ; but I have not seen it recorded that 

 the division between the two elements can be observed in the 

 adult condition. That such, however, is sometimes the case is 

 proved by a mounted skeleton of Bradypus in the Natural History 

 Museum, of which the right half of the pectoral girdle (exclusive 

 of the clavicle) is represented in the drawing now exhibited (see 

 woodcut, p. 173, fig. 1). The suture, although anchylosed, is dis- 

 tinctly visible, and shows that the coracoidal element forms a small 

 moiety of the glenoid cavity ; the suture passing from the latter to 

 the upper border of the coraco-scapular foramen, and being con- 

 tinued from the lower edge of the latter to the free lower margin 

 of the compound bone. I have also observed the coracoidal element 

 perfectly distinct in the skeleton of an immature Sloth in the 

 Museum. 



The large size and the distinctness of the coracoidal element in 

 the pectoral girdle of the Sloth appear to me to afford consider- 

 able support to the view that the Edentates form a group of equal 

 value with the typical Eutheria. 



