676 DR. p. CHALMERS MITCHELL ON THE 



The strong proximal anchor (text-fig. 128, 3) ito the humerus also 

 occurs in many Steganopods, in Storks, Herons, and is probably 

 representeil in ScojJits, in which bird Beddard mentions a strong 

 insertion to a fibrous aponeurosis attached to the crista of the 

 humerus and covering the biceps. It is characteristic of Storks 

 as opposed to Herons, that in the former birds the great pectoral 

 is completely divided into two msucles, as it is in the Pelican 

 and some other Steganopods. The insertions of these portions as 

 described by Weldon correspond almost exactly with the double 

 insertion in JJalceniceps, and I was able to separate the mass of 

 muscle quite easily into portions corresponding with these inser- 

 tions, although, in the absence of the separate insertions, I should 

 not have described the muscle as doubled. But, whatever the 

 distinction be worth, the great pectoral muscle of Balceniceps in 

 more Ciconine than Ardeine. Beddard's description of the condi- 

 tion in Scopus is not sufticiently detailed to follow in this matter, 

 but he speaks of it as " partly doubled," and the humerus shows^ 

 marks of a, double insei'tion. 



Fectoralis propatagialis (text-figs. 126, 128, pp. 671, 675). — As I 

 have already stated, there are separate slips from the pectoral for 

 the longus and brevis tendons. Both slips are entirely tendinous, 

 and that for the longus is smaller and more suparficial (text-fig. 

 126, P.I., P.b. ; text-fig. 128, P.pt.). In my dissections of Herons,. 

 I find similaxly distinct slips for the brevis and longus from the 

 pectoral ; Beddard mentions them for Scopus, but- in the case of 

 Storks the usual arrangement appears to be the more primitive 

 condition of a, single slip, which joins the patagial tendon before 

 that has divided into longus and brevis. 



PectoraUs ahclominalis. — This is absent in Bcdcenicejjs as in 

 Storks. It is present in Herons, but Beddard does not refer to 

 its presence or absence in the case of Scopus. 



Supracoracoideus [PectoraUs minor). — This is a small and 

 rather naiTOW muscle elongately oval, with a centrally placed 

 tendon like the mid-rib of a leaf. Its fleshy origin is limited to 

 a very small part of the sternum, including no part of the keel, 

 and part of the coracoid and the membrane between the coracoid 

 and clavicle. It is Avidely separated on the coracoid from the- 

 origin of the coracohrachicdis 'posterior (pectoralis tertius) and its 

 tendon of insertion (text-fig. 128, Su.) is free from any fibres- 

 that could represent a deltoides minor. Its general relations and 

 small size are closely paralled in Herons and Storks. 



Coracohrachialis externus or anterior. — A strong muscle arising 

 fleshy from the acrocoracoid only (text- fig. 128, Cor. ex.) and 

 covered only at the extreme edge by the tendon of origin of the 

 biceps. Insertion on a broadly oval area to the jilanum bici^iitale 

 of the humerus. 



Coracohrachialis internus {Pe?:toralis tertias). — A very stout 

 almost doubled mass of muscle from the distal dorsal two-thirds 

 of the edge of the coracoid opposite the origin of the supracora- 



