374: Transactions of the South African Philosophical Society. 



almost constantly used in a different sense. Precoracoid is, on the 

 other hand, well established as the name for the anterior element. 



It seems to me inadvisable to give a special name to the inferior 

 cartilaginous margin of the coracoid. In no animal is it ever a 

 distinct bone. Most cartilage bones have their ends tipped with 

 unossified cartilage, and even when a special ossification appears in 

 the end cartilage it is only spoken of as an epiphysis. If phylo- 

 genetically reason could be shown for believing the cartilaginous tip 

 to be the remains of an element once clearly distinct a special name 

 might perhaps be given to it, but the name could not be 

 " epicoracoid." 



The primitive reptilian shoulder girdle consisted of three cartilage 

 bones — scapula, coracoid, and precoracoid, and two membrane bones 

 — the clavicle and cleithrum, with in the middle line an inter- 

 clavicle. In only the most primitive reptiles and the Synapsida 

 is the cleithrum met with, and very early in the Diapsidan phylum 

 was the precoracoid lost. In no Diapsidan reptile is it known tO' 

 occur after Permian times. Even in the very early Palceohatteria it is 

 already lost — at least as on ossified element ; and in Sphenodon there 

 is no trace of it to be found in development. And there is good 

 reason to believe that an element once lost in an ancestor can never 

 be regained in a descendant. Various modifications may take place 

 as in the ostrich, tortoise, plesiosaur, &c, but a distinct precoracoid 

 never reappears. All the various anterior expansions of the scapula 

 and coracoid in the typical lizard are likely to be only developments 

 of the scapula and coracoid. 



In the very aberrant lizard Ghamceleo a peculiar condition of the 

 shoulder girdle is met with, which strikingly recalls that of Spheno- 

 don, and is possibly primitive. It is usually described as consisting 

 of a narrow scapula and a rounded coracoid with no trace of a 

 clavicle or interclavicle. In examining the embryo I have dis- 

 covered that a fairly well-developed clavicle is present, best seen 

 perhaps in an embryo, about one-fourth of adult size. There is no 

 trace, however, of an interclavicle. Another point of interest is 

 some indication of an acromion process in the lower end of the 

 scapula passing a little further forward than the coracoid. 



In the typical lizard the peculiar arrangement has probably arisen 

 by the scapula and coracoid becoming expanded in an anterior 

 direction, and at the same time the expanded part becoming 

 fenestrated. This seems to be borne out both by the developmental 

 condition and by the comparison of the different types found. As 

 shown by Parker in Laemanctus only the coracoid is fenestrated by 

 a single large opening. In Psammosaurus the scapula is but little 



