1893.] 



OF THE TEBBESTEIAL VERTEBBATA. 



589 



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

 extends rapidly, and first ankyloses, no 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 tlie 

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



Fiff. 1. 



The Coracoid Apparatus. 



la. Zep2<i', one month after bird] ; \b. Zfjozfs, 7 weeks, both X H. \c. 8civrui> 

 vulgaris, '^as. ; \d. Bradypus cuculliger, jiiv., both X 2. 1 e. L'holwptif, 

 didacti/ius, half-grown, uat. size. \f. Tamandua tetradiicfyla, front 

 view, adult, X 1^. 1 g. Tatusia noverncincta, inner aspect, X \\. 1 h. 

 Atehf, marghiatns, X H. 1 i. Cehus sp., X IJ. 1 k. Homo, 14-15 

 years, modified from Sabatier, ^ iiat. size. 



ac. Acromion. Co' . Epicoracoid. Co" . Metacoracoid. So. Scapida. ep. Scapu- 

 lar epiplijsis. fo. Coracu-.scapular foramen. 



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

 that the interpretation of Lydekker cannot hold good for the 

 Sloths as a series. In justice to myself, 1 am tlierefore compelled 

 to add Ihat, so far as ilie point immediately at issue is concerned, the 

 ground trave'-scd by Mr. Lydekker has been already covered in my 

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

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

 at any i-ate in ils non-reduced form. 



I have observed the existence of a distinct metacoracoid in tlie 



