1893.] ON THE C0B.AC01D OF THE TERRESTRIAL VERXEBRATA. 585 



7. On the Coracoicl of the Terrestrial Vertebrata. By G. B. 

 Howes, F.Z.S.^ F.L.S., Assistant Professor of Zoology, 

 Boy. Coll. Sci. Lond. 



[Received June 20, 1893.] 



1. As to Terminolog ij . 



It is now generally conceded that some of the Anomodont 

 reptiles, which in many respects so closely approximate towards 

 the Mammalia in their skeletal anatomy, were possessed of an 

 expanded epicoracoid of the Monotreme type. Professor Seeley, 

 to ^^"hom we are chiefly indebted for tlie discoveries which ha\ e 

 rendered this conclusion clear, discards the Cuvierian term " epi- 

 coracoid'' and persistently applies the term prec<n'acoid to the 

 element in question in both reptiles and mammals \ 



In this he is followed by Mr. Hulke". Mr. Lydekker, however, 

 in a recent communication to this Society ^, has proposed to abolish 

 the term epicoracoid altogether, in association with a discovery of my 

 own' that the element to which in the Monotreme the term ' epi- 

 coracoid ' was first applied is the serial homologue of the coracoid 

 process of the higher mammals, to which, in the long run, the 

 term ' coracoid ' was originally given. 



The term pi-ecoracoid (pi'ocoracoid of G-egenbaur) is well known 

 to be used in two or more totally distinct senses (sometimes by the 

 same observer in the same paper '). It is for the most p'art either 

 applied to a mere process of the coracoid, most variable in its 

 relationships when present and in no sense originally distinct, 

 or restricted to that bar which underlies the clavicle^ and (some 



' Cf. Phil. Trans. 1888, B. pp. 400-492, 1889, B. pp. 265 and 275, aud 

 P. R. S. Tol. li. p. 119. 



2 P. R. S. vol. li. p. 233. 



3 See P. Z. S. 1893, p. 172. 



* Journ. Anat. & Pliys. vol xxi. p. 192. 



' Cf. Hulke, loc. cif. description of figs. 4, 6, 7, nnd 9. 



* Goette, as is well known, confirmed Rathke's discovery of this '" Anlage " in 

 the young liziird. The contradictory arguments vvhicli have been based upon 

 its supposed distinctness or non-distinctness in this or that aniujal lose their 

 force to-day in the tendency of recent researdi to demonstrate, more and more 

 clearly, that tlie tliree great elements of both the ])ectoral and pelvic girdles 

 are at first independently ditierentiated. (C'f. especially tlie pajiers of Miss 

 Lindsav in P. Z. 8. IH,'^;'), p. (192, and of Mehnert in Morph. Jahrb. Bd. xiii. 

 p. 293,& Bd. XV. p. 1 10). 



There can, I think, belittle doubt that the Rathke-Parker conclusion that the 

 dermo-claviunhii- elements are in the Chelonia represented by thcecto-and enlo- 

 plastra is correef. It a])pears to luc iiiglily probable tiiat in these animals the 

 claviculo-coracoid apparatus has undergone a kind of analysis into its consti- 

 tuent elements, and that the precoracuid (in the non-diU'ereutiation of a distinct 

 endosteal centre within its substance, such as CJcgenbaiir fiist. described for 

 man himself) has become ossified by an extension of the acromial tract. Baur 

 lias lately proposed to term this ajiparcnt acromion a ' ))ros('apula ' (r/". I'ror. 

 Acad. J«at. Nci. i'hiiad. 1>S91, p. 424), a by no means inappropriate lerm, if a 

 new fjne be necessarv. 



