MACALISTEIl — ON THE MUSCLES IN CEllTAIN MONKEYS. 35 



The principal muscular characteristics of the Quadrumanous type, 

 which are recognised by comparative anatomists, are — The absence of a 

 distinct long flexor for the thumb ; the elevation of the rhomboideus, 

 which is usually single, to the occiput; the presence of a trachelo-acromial 

 or omo-atlanticus muscle, which in some few individuals exists as a le- 

 vator claviculaB ; a rectus thoracicus ; the prolongation of the insertion 

 of latissimus dorsi to the olecranon process, or the origin of ahead of the 

 triceps from that tendon; or the existence of a separate dorso-epi- 

 trochlear muscle; the downward prolongation of scalenus posticus to 

 the third, fourth, and even fifth ribs ; the absence of a coronoid head 

 for the pronator teres, or of a radial origin for the superficial flexor 

 digitorum manus ; the union of the lower border of the levator anguli 

 scapulse with the upper edge of the serratus magnus ; the extension of 

 the insertion of the indicator muscle to the middle finger as well as 

 to the index, likewise of the extensor minimi digiti to the ring as well as 

 to the fourth finger. All of these may not coexist in every individual of 

 the order, but their presence, in whole or in part, indicates an approach 

 or relationship more or less close to the Quadrumanous type. 



A few remarkable muscular arrangements, not included in the pre- 

 ceding list, have occurred in my dissection of monkeys of several species. 

 Firstly, in Cebus capucinus, two specimens of which I have examined, 

 the chief features of interest were found in the disposal of the pectoral 

 muscles ; as, when the pectoralis major was reflected, three muscles were 

 brought into view beneath it — the first, or ordinary lesser pectoral, 

 whose attachments were normal ; secondly, a slender chondro-humeral 

 muscular fasciculus, which ran from the cartilages of the seventh, eighth, 

 and ninth ribs, to be inserted into the outer lip of the bicipital groove, 

 quite separate from the pectoralis major, and inserted internal and su- 

 perior to that muscle. The third chondro-capsular portion, which lay still 

 deeper, arose from the cartilages of the eighth, ninth, and tenth ribs, 

 and, crossing behind the last-named portion, was inserted into the cap- 

 sular ligament of the shoulder joint, inferior to the insertion of the pec- 

 toralis minor. This portion corresponds with the lower part of the 

 lesser pectoral described by Mivartin Cercopithecus sahceus* These latter 

 portions were both directed upwards and outwards, but with such dif- 

 ferent degrees of inclination, that the latter crossed beneath the second, 

 and was inserted superior and internal to it. Of these three the last 

 may probably be the homologue of a third pectoral, while the second 

 slip is mayhap but a perfectly differentiated slip of the lower costal 

 fibres of the great pectoral. And this view is strengthened by the fact 

 that in an undetermined species of Macacus, probably a variety of M. 

 nemestrinus, I found an arrangement somewhat similar to that above 

 described, except that the second deep slip was at its origin slightly 

 connected to the great pectoral. 



On raising this series of muscles the supra-costalis or sternalis bru- 



* "Proceedings of the Zoological Society," 1865, p. 44. 



