336 TRANSACTIONS OF THE [OCT. 4, 



especiall}' to Lemur catta. For this reason, and because the 

 species is not included in the list of those examined hy the 

 above named authors, I present some of the results of our dis- 

 sections for the consideration of the section. I am, moreover, 

 fully persuaded of the necessit}' of multiplying careful and ac- 

 curate observations in comparative myology, in order to obtain 

 a satisfactory knowledge of the structure of any given family 

 or species. Our observations on a fairly large number of cyno- 

 morphous monkeys have convinced me that for purposes of gen- 

 eralization the results obtained by the examination of one or 

 two specimens are frequentl}' misleading, as a not inconsiderable 

 range of variation is encountered in these forms. 



The present paper deals with some of the muscles of the 

 trunk, and of the scapulo-humeral and brachial groups. 



1. Pectorals. 



J/m. Pectoralis major and minor (Ectopectoral and Ento- 

 pectoral, Wilder) are both present. 



A. M, Pectoralis Major, Ectopectoral. 

 PL XXVIII.-XXXI., inch PL XXXII., Fig 7. PI. XXXIV. 



Origin. — Sternal extremity of clavicle,''ventral surface,*for ^ 

 cm.; ventral surface of sterno-clavicular articulation ; obliquely 

 across presternum to midsternal line ; in close connection with 

 the muscle of the opposite side, by short tendinous fibres from 

 the middle of the ventral surface of the mesosternum along the 

 entire length of the bone (PI. XXVIII." and XXXIV.) 



At the junction of meso- and poststernum the line of attach- 

 ment is deflected laterad, and the muscle arises from the dense 

 sheath of the abdominal Rectus and from the aponeurosis of the 

 External oblique muscle. This abdominal origin extends caudad 

 to the junction of the middle and posterior third of the cephalo- 

 caudal body measurement. It forms a sharply defined, slightly 

 notched line, concave cephalad, curving dorsad and caudad from 

 the poststernal articulation, the muscular fibres arising directlj^ 

 from the abdominal aponeurosis (PI. XXVIII and XXXIV.) 

 There is no approach to the formation of the thin musculo-ten- 

 dinous plane so characteristic of the abdominal Pectoral in Apes, 

 which can be reflected nearly to the median line between post- 

 sternum and umbilicus. In Lemur the abdominal portion of the 

 muscle arises directl3^ by strong muscular fibres from the exter- 

 nal oblique aponeurosis along the line indicated. 



There is a cellular interval, forming a narrow cleft, between 

 the clavicular and sternal divisions of the muscle. Lisertion 

 will be considered with that of the Pectoralis minor {Ento- 

 2:>ectoral'), with which it is in part combined. 



