1894.] ANATOMY OF ORKITHORHTJSTCHUS. 695 



of opinion during recent years as to the value of nerve-supply 

 in determining muscular homologies, the present seems opportune 

 for a re-examination of the limb myology, and a description of the 

 nerve-plexuses of this animal. 



I injected the animal with the intention of giving an account 

 of the vascular system, but as I proceeded I observed that an 

 investigation of the arterial and venous systems would be more 

 successfully undertaken upon a fresh specimen. I have incorpo- 

 rated a few preliminary observations on the trunk and head 

 arteries, and I hope to give a complete description of this part of 

 the anatomy of the animal. 



My best thanks are due to Professor Windle for kindly pro- 

 viding me with the specimen. 



Trapezius. — This muscle consists of two portions, an anterior 

 and posterior. The upper portion is broad. It arises from the 

 occipital bone and from the ligamentum nuchae. It is inserted 

 into the spine and acromion of scapula and into the outer third of 

 clavicle. The lower portion is triangular in shape. It arises from 

 the seventh, eighth, ninth, and tenth dorsal vertebrae, and from 

 the ninth, tenth, and eleventh ribs. It is inserted by its narrow 

 apex into the spine of the scapula. Both parts of the muscle are 

 supplied by the same nerve : this passes out just below occiput, 

 gives small branches to anterior part, turns round posterior edge 

 of this portion of the muscle, and ends in posterior part. 



Latissimus dorsi. — This muscle has an extensive origin from 

 the lower eleven ribs, all the dorsal and lumbar vertebrae, and the 

 crest of the ilium. It is inserted by two portions, upper and 

 lower, into the humerus, reaching down nearly to the elbow. 

 Both parts are supplied by a nerve derived from the seventh 

 cervical. Coues speaks of the slight spinal and extensive costal 

 origin of this muscle l , Costal origin seventh to fourteenth ribs. 

 Spinal origin from dorsal vertebrae fourth to ninth. No lumbar 

 origin is mentioned by him. I found both origins more extensive 

 than those mentioned by Coues, and agreeing more with the 

 description given by Owen. The muscle gives off a distinct dorsi- 

 epitrochlearis. 



Ehomboideus. — Is a single muscle having both an occipital and 

 a nuchal origin. It is inserted into the base of the scapula. 



Epicoraco-brachialis. — This is a triangular muscle. It arises 

 from the epicoracoid and is inserted close to the anterior portion 

 of the deltoid. 



Pectoralis major. — This is a large muscle, extending posteriorly 

 almost as far as pubes. It arises from the sternum and from the 

 upper six ribs. The lower part unites with the muscle of the 

 opposite side in a thin aponeurosis. It is inserted into the 

 pectoral ridge of humerus. The muscle is supplied by a large 

 nerve derived from the front of the lower trunk of brachial plexus. 

 It divides into several branches before passing to the muscle. 



Levator anguli scapulce (Trachelo-scapidar). — This muscle arises 

 1 Vide Proceedings of Essex Institute U,S. vol. ri. 18fi8, p. 142, 



