The Morphology of Cosmobia 



4i; 



divarication of the two axes in the doubled region. This gives the double 

 and single axes a relation like that of the three elements of the letter 

 Y, and the relation of the plane of the section to these can be readily 

 seen if we imagine this letter crossed by numerous parallel lines perpen- 

 dicular to the stem. The arms will be cut obliquely and, in the case of 



Fig. 28a 



Fig. 28. Two sections from the cross-series made from Teras I. 



(a) Section 180. At the level of the two inner eyes. The nerve cut 

 longitudinally and placed the most lateral is the Trochlearis ; its supply to 

 the superior oblique is also seen. Behind this is the Motor oculi, cut trans- 

 versely. The median ganglion, with a nerve branching from one side, is the 

 median Trigeminus, with the ophthalmic branch, and the smaller median 

 nerve, directly behind it is the Abducens. 



paired organs placed directly opposite each other with reference to either 

 of these, the inner one will be cut first. This is why in this series the 

 two median eyes appear on more anterior sections than those which show 

 the lateral ones, and it explains also why in the first of the two sections 

 given each fore-brain is cut obliquely with its inner side considerably in 

 advance of the outer. Between these two fore-brains lies the region of 



