134 MDWARD PHELPS ALLIS, JUN. 



dorsal edge of the other. This bundle lies ventral to both 

 the oculomotorius and ophthalmicus profundus nerves, near 

 tlieir exits from the cranium, and also ventral to the proximal 

 end of the rectus inferior muscle. The other, smaller and 

 dorsal bundle of the muscle separates, proximal ly, from the 

 ventral bundle, and running- backward and dorsally, dorsal 

 to the inferior division of the oculomotorius, to the ophthal- 

 micus profundus, and also to the proximal end of the rectus 

 inferior, comes into contact with the ventral edge and inner 

 surface of the rectus superior. There it gradually diminishes 

 in size, and disappears without ever having reached the car- 

 tilage of the skull. The dorsal bundle thus lies always dorsal 

 to the inferior division of the oculomotorius and to the pro- 

 fundus nerve, while the ventral bundle lies ventral to both 

 those nerves at and near their exits from the skull. Farther 

 forward this ventral bundle of the muscle lies dorsal to the 

 profundus, the profundus passing downward along the lateral 

 surface, and then forward across the ventral edge of the 

 muscle. 



The only part of the internus of my embryo that has an 

 origin on tlie skull thus differs from the muscle as shown by 

 Tiesing in the adult (62, figs. 1 and 5) in that it has a 

 different origin, markedly different relations to the oculomo- 

 torius, and somewhat different relations to the ophthalmicus 

 profundus. The muscle of the adult is shown by Tiesing 

 arising from the skull dorso-anterior to the profundus fora- 

 men, and from there running forward dorsal to both the 

 inferior division of the oculomotorius and to the profundus. 

 In Tiesing's figure the ocumolotorius is not shown perforating 

 the rectus superior, although it is said in the text to perforate 

 that muscle. 



Corning (14) finds the inferior division of the oculomo- 

 torius of the adult Mustelus perforating the rectus internus, 

 as Schwalbe did before him, but he does not give the rela- 

 tions of the prof undus nerve to the muscle. Schwalbe says 

 that this latter nerve also perforates the muscle, near its hind 

 pdge, and then runs forward below it, 



