of the Pelvic Plexus in Acanthias vulgaris. 



15 



rostral portion of the fin, it has not been thought necessary to con- 

 sider the two sexes separately on this point. The following table 

 shows the way in which the variations in the position of the first 

 girdle-piercing nerve are associated with the variations in the number 

 of the collector nerves. 



Table VIII. 



From this table it will be at once seen that the more rostnil position 

 of the girdle is on the whole correlated with a reduction in the 

 number of nerves taking part in the formation of the nervus collector. 

 The only break in the ascending series of the average number of 

 collector nerves as the girdle becomes more caudal, occurs where the 

 girdle is pierced by the thirty-seventh and thirty-eighth nerves. 



Here the average number of collector branches is practically identical 

 in the two cases. The criticism may be made that a number of old 

 embryos are included in the above table, and that, if we may judge 

 from the case of Mustelus ((12), p. 335), these may show a larger 

 number of collector branches than the adults, and so tend to bring 

 irregularities into it. Such a criticism may be disposed of by the 

 following two tables, in which a comparison is made between such 

 embryos and the adults. 



Table IX. 



Table X. 



