284 Proceedings of the Royal Society of Victoria. 



this we have only indirect evidence, 

 to VIII., we notice in Fig. 3 a 

 gradual but certain advance in this 

 direction. 



A somewhat peculiar exception 

 to this is seen in forms ii. and iii. 

 in the figure, which would seem to 

 reverse the natural order, but in 

 the face of the evidence given 

 for those two forms in the table, 

 form iii., certainly occurring with 

 a higher thickness than ii., I have 

 not felt justified in changing the 

 order, though it would certainly 

 appear that a form in which the 

 criiralis contains X. fibres, as well 

 as IX. and VIII., would be more 

 primitive than one in which only 

 IX. and VIII. fibres occur. This 

 deviation, however, is not nearly 

 sufficient to nullify the evidence 

 of the rest of the table, which 

 entirely agrees with Adolphi's 

 results for Bujo variabilis, viz., 

 that " nerve VIII. originally 

 destined for the body wall (by 

 the ileo-hypogastric) is passed 

 over to take care of the leg (by 

 the criiralis), and gradually gains 

 an ever-increasing value in that 

 direction." 



I have also drawn up a Table 

 (E), which should show the rela- 

 tions between the thickness of 

 nerve IX. and the form of the 

 criiralis, if any exist. There is a 

 somewhat regular progression in 

 forms i. to v., but forms vi., v i i . , 

 and viii.j are very irregular : also 



