30 



\K\v\ (lus iiniscio Willi l\v(i liivfi's; willi mail and willi ( 'i'rc()|iitlicciis 

 cyiiosiinis on llie conlraiy tlie iM. ol)li(|. inl. shows in iIk^ cranial 

 |)art two layers, and |tasses candally eniirely into the anterior wall 

 of the Vagina M. recti. 



In the relation tiie M. ()iili(|. inl. hears to the M. rectus conse- 

 (incntiy tliree ty|)es can l»e dislingnishcd : the M. oi)ii(|. int. runs 

 either entirely l»ehind the M. rectus, or pas.scs eniirely into the 

 anterior lamella of the sheath, or heha\es differently, with regard to 

 the M. rectns, in the cranial part than in the candal part; now the 

 ([iiestion rises which of these conditions is the original one. It is 

 self-evident, that the condition of the M. ohliq. inl. in which the 

 relation to the M. rectns in the cranial part is so qnite ditferent 

 from that in the caudal part will not have existed with (lie ancestral 

 forms of Primates. With these doubtless the relation of the M. obliq. 

 int. to the M. rectns will have answered to one of the two other 

 types; conse(|nently the M.. oblicp int. has originally taken part either 

 in the forming of the anterior or in that of the posterior lamella 

 of the sheath of the M. rectns. 



As we are compelled to admit witii regard to the M. transversus, 

 Ihat this muscle was pierced in the course of the j)liylogeny by the 

 M. rectus, it is a priori veiT likely that the piercing of die M. obliq. 

 int. will depend upon the same cause that also brings about the 

 moditication in the course of the M. transv. From this simple con- 

 sideration results the conclusion that originally the M. obliq. int. 

 pas.scd presumably behind the M. rectus. 



Comparative anatomy can likewise support our \iew, that orij^inally 

 with Primates the M. obliq. int. is situated behind the M. rectus. If 

 namely we consider the relation of this muscle to the M. rectus 

 with diU'erent Vertebrates (Maurer) we tind that with Urodeles the 

 ,M. (ilili(|. inl. [lapses continuously into the M. rectus, with Anures 

 this muscle exists only in the larva, with Reptiles, however, we tind, 

 thai, where a M. obliq. int. exists as such, it has disengaged itself 

 frnm liio system of the Musculi recti and possesses an aponeurosis, 

 that runs behind the M. rectus abdominis. 



The }{('inl>rana aMoDiini.t inter media with ail Katarrhini takes 

 part ill the foiauing of the anterior lamella of the sheath ; this cannot 

 be otherwise, as both the M. obliq. ext. and the M. obliq. int. iia.s9 

 in front of the M. rectus. In case, however, as with Platyrrhiui, the 

 M. oliliij. int. in the cranial part lies behind the M. rectus, the 

 membrane also lies in the cranial part behind it. In the caudal 

 part we lind nowhere the membrane behind the AI. rectus : with 

 Ateles paniscus it is connected at the lateral edge with the peri- 



