350 TRANSACTIONS OF THE [oCT. 4, 



This arrangement seems to correspond most closel}- to that 

 found by us in L. bruneus, except that in this animal the thoracic 

 prolongation of the muscle caudad of the first rib extends to the 

 fourth and fifth ribs, whereas in L. xanthoviystax it occupies the 

 second, third and fourth ribs. 



Galago crassicaudatus,a.ccov^\r\g to Murie and Mivart (1, p. 

 23), agrees with L. varius. 



In Galago allenii the authors found a small anterior Scalenus 

 passing to the first rib in front (ventrad) of the lowest nerve of 

 the Brachial plexus; also a Scalenus mediusand posticus, arising 

 from the fourth to the sixth cervical transverse processes (costal 

 attachment is not described). 



Burmeister (6, p. 37, tab. 4, fig. 9, c, c, c,) describes three 

 Scaleni in Tarsius spectrum, arising from the first three ribs and 

 going to the sixth to the first cervical vertebrae. 



Allen (13, p. 41) mentions, but does not describe, the muscle 

 in Tarsius fuscus. Murie and Mivart find that in Gheiromys the 

 muscle is arranged as in L. catta, except that the " anterior " 

 portion extends " back " to the fourth rib. (It is diflScult to 

 see what is meant by " anterior " in this connection, whether 

 the ventral or cephalic portion of the muscle. In a foot-note it 

 is stated that the muscle is the "Scalenus posticus " of Meckel, 

 p. 159.) 



Lucae (12? p. 35, tab. II, 19) describes and figures a 

 " Scalenus minor " in Lemur macaco as a strong, broad muscle, 

 arising from the first rib and passing to the transverse processes 

 of the six lower vertebra ; also a " Scalenus major," united 

 above with the minor and descending as a slender muscle on the 

 lateral aspect of the thorax to the fourth rib, external to the 

 Rectus muscle. Between these two muscles the cords of the 

 Brachial plexus emerge. 



This is the only instance described among Lemurs in which 

 the relation of the Scalenus group to the fore-limb nerves is the 

 same as in the higher Primates, although the condition found in 

 this animal is foreshadowed by the small anterior scalenus of 

 Galago allenii^ passing ventrad of the lowest nerve of the 

 Brachial plexus. 



6. M. Obliquus Externus Abdominis. 



(PI. XXVIII. and XXXIV.) 



Origin: Ectal surface and caudal margin of the nine caudal 

 ribs, the five cephalic slips interdigitating with the Serratus an- 

 terior. Also from the strong lumbar aponeurosis and from the 

 ventral end of the iliac crest. 



