18 PROCEEDINGS OF THE NATIONAL MUSEUM VOL.80 



As it is likely that all parts of the present coracobrachialis are 

 derivatives of one original component, the terms by which we desig- 

 nate the several divisions that may occur are not of paramount 

 importance, but at least they should be uniformly applied. For the 

 reason that there has been so much confusion in the treatment of the 

 so-called long division, we prefer to abandon this term in favor of 

 " superficialis." 



Occasionally in man there occurs a coracobrachialis brevis, or 

 "profundus," as we designate it (also termed coracocapsularis, cora- 

 cobrachialis superior, coracohumeralis superior, and rotator humeri). 

 Eisler (1895) saw it at least twenty times in nine years, and Wood 

 reported that he had met with it four times. Among 39 arms (24 

 negro, 15 white), representing 20 individuals (12 negro, 8 white), 

 examined carefully for this detail, we found a coracobrachialis pro- 

 fundus in three instances (2 negro, 1 white). In each case the 

 nerve supply had unfortunately been destroyed before we saw the 

 muscle. These three examples exhibited certain differences in their 

 morphology, and it seems worth while to describe them in some detail. 



In the left arm of an extremely muscular male negro a coracobra- 

 chialis profundus arose from near the tip of the coracoid process as 

 a broad and fleshy slip, which inserted above and behind the latissi- 

 mus dorsi tendon. The coracobrachialis proprius (or medius) ex- 

 hibited its customary relations, and it was pierced as usual by the 

 musculocutaneous nerve. Upon the right arm the profundus element 

 was entirely absent. 



The second example of this muscle was found in the right arm 

 of a well-developed male negro. It arose from near the anterior 

 end of the coracoid process and continued fleshily to insert above and 

 behind the latissimus dorsi tendon ; and likewise by a short, tendinous 

 extension upon a second, long tendon, which arose from the surgical 

 neck of the humerus and which continued distally to pass uninter- 

 ruptedly into the medial intermuscular septum. The coracobra- 

 chialis proprius was quite normal and was pierced by the musculocu- 

 taneous nerve. There was no trace of a coracobrachialis profundus 

 upon the left arm. 



The third occurrence of this slip was upon the right arm of a 

 male white. It was unusual in that it arose not from the coracoid 

 tip, but broadly and fleshily from the medial border of this process 

 for a considerable distance. It inserted above the latissimus dorsi 

 tendon. The coracobrachialis proprius was normal and was pierced 

 by the musculocutaneous nerve. The left arm exhibited no trace of 

 a profundus element. 



In primates the coracobrachialis profundus is a short and rela- 

 tively broad, entirely fleshy slip arising either from the deep part 



