20 



soiiielliiiiii!; i.s coinmiiiiiciiled aliout llic coiniiaialuc aiialonn ot' llio 

 reotal slifalli of Priinalofs. 'J'iiis snlijecl Imwovt-r (Icsorves «rreafer 

 attenfioii, as tVoiii a few stray ('oiuiniiiiications il a|t|)eai's, tliat (lie 

 sd'uodire ot' tlie slieatli of the dilfereiit s[)e('ies of Primates can show 

 ratlier consideralilo differences. 



I shall conimunicatc here shortly the resiills of an investigation 

 into the comparative anatomy of the sheath of the rectus muscle 

 made by mc in tlie Anatomical Laboratory of Amsterdam. In this 

 conimnnication I shall leave Prosimiae entirely out of consideration, 

 and conse(|uently restrict myself to Sindae fPlatyri'hini and Katai'rhini) 

 and llominiilae. 



( >n lilt' Mciii/ii'iuiii a/i(l<niiinis inti'vmediit. 



As the first result of my investigation I can communicate, tiiat 

 with all monkeys examined by me, both Katarrhini and Platyrrliini, 

 a fourth element participates in the formation of the sheath of the 

 M. rectus, besides the three Hat muscles of the abdomen. Between 

 the M. obliquus externus abdominis and the M. obliquus internus 

 abdominis a fascial uieiubraiie is namely found. This membrane 

 is solid, admits of a good free pre|)aration, consequently it distin- 

 guishes itself obviously from the tlimsy connective tissue, which is 

 found in man between the Hat muscles of tjie abdomen. In the lite- 

 rature this membrane is not mentioned ; I shall designate it as 

 Mi'iiihrana /ihdontini.i iiiteiinedin. The anatomical lines of demarca- 

 tion of this membrane can dislinctiy be indicated. In the caudal 

 part tiie origin is immediately connected with that of the M. obliq. 

 int. : the membrana interm. is attached to the fascia lumbodorsalis, 

 crista iliaca. s|)ina iliaca anterior and follows also in a caudal 

 direction the origo of the M. obli(|. int.. so that — with a powerful 

 development of the membrane - its last fibres aie attached to tiie 

 ramus snpti'ior ossis pubis. Sometinu's however it cannot be followed 

 as far as the origins indicated here : in these cases it is closely con- 

 nected with the M. obliq. int., because it origiiuxtes in the perimysium 

 e.xternnm of the latter at some distance from the origo of that muscle. 

 In the cranial part the origin of the membrane cannot be indicated 

 so exactly : it is namely continued between the M. obliq. ext. and 

 the thoracal wall, and looses itself in the flimsy connective tissue 

 that is found here. An origin from ribs can consequently not be 

 ascei-laiiied. 



In a me<lian direction the mend^rane passes into the sheath of the 

 M. rectus in the forming of which ii takes part with the three flat 

 mus(des of llic abilomen. 



