1893.] 



OF THE TERRESTEIAL YERTEBEATA. 



589 



exceedingly brief (from two to three weeks in Lepus} ; it arises late,- 

 extends rapidly, and first ankyloses, do less summarily, with either 

 the scapula or epicoracoid. It is therefore a difficult structure to 

 detect, unless we examine a large series of specimens of all ages. 

 In view of these facts, the further study of the Bradypodine girdle 

 can alone show what is the actual share of the coracoid centres in the 

 adult glenoid cavity of that animal ; but, be the outcome of this what 



Fig. 1. 





The Coracoid Apparatus. 



la. X«p«s, one month afterbirth ; \b. ipjo!<*-, 7 weeks, both x 14. 1 '". Sriunis 

 vtdgaris, jav. ; \d. Bradyptis cunilUger, juv., both X 2. \ e. Choloejms 

 didacft/lua, lialf'-grown, nat. size. 1./'. Tamandua tetradacfyla, front 

 \g. Tatusia novemcincta, inner aspect, X 1^. 1 h. 



view, adult, X 1^. 



Atelcs margin at us, X 1^. 1 i. Cehus sp., 



years, modified from Sabatier, i nat. size. 



X 1*. 1 k. Homo, 14-15 



ac. Acromion. Co' . Epicoracoid. Co". Metacoracoid. Sc. Scapula, ep. Scapu- 

 lar epipliysis. fo. Coraco-scapular foramen. 



it may, the condition of the Choloepine girdle (as here figured) shows 

 that the interpretation of Lydekker cannot hold good for the 

 Sloths as a series. In justice to myself, I am therefore compelled 

 to add that, so far as tlie point immediately at issue is concerned, the 

 ground traversed by Mr. Lydekker has been already covered in my 

 earlier communication, and I regret that in my later one, which he 

 cites, I did not add, after the words " most characteristic features," 

 at any rate in its non-reduced form. 



I have observed the existence of a distinct metacoracoid in the 



