918 THE VOYAGE OF H.M.S. CHALLENGER. 



development of the seventh pair of appendages without much change in the form of the 

 animal that he was induced to believe in its adult condition. 



" The form of the antennae, and of the seventh pair of legs, the structure of the 

 branchiae, of the appendages of the pleon, and of the sexual apparatus must be more 

 fully known before the question of the adult condition of the animal can be looked upon 

 as decided. Under all the circumstances I was justified in considering as larval forms 

 the largest specimens with which I was acquainted, and which possess the seventh pair 

 of appendages in a rudimentary condition, rudimentary branchiae, and the pleopoda 

 without hairs, in accordance with Dohrn's description, and also in prostesting against 

 interpreting as an ovary the mass of cells with its opening, on the basis of the descrip- 

 tion and figure of the last-mentioned author. 1 If Arn/phion in an unchanged form really 

 becomes an adult animal, we have in it a new and interesting form of Schizopod, in 

 which the maxillae and gnathopoda (vorderen Kieferfiisse) — as is also the case in Petal- 

 ophthalmus and Chalarasjris — indicate a transition to the Decapoda, and in which the 

 carapace already overlaps all the pereionic somites." 



The view that these several forms of Am/phioii suggest, is that from the brephalos to 

 the adult animal the development is regular with the growth of parts, but that as yet 

 we have not obtained the earliest nor reached the latest stage of growth. What the 

 latter stage may be can only be surmised, but I believe it cannot be very distinct in its 

 external characteristics from that of the oldest known specimen of Amphion. The form 

 and nature of the branchial plumes demonstrate that it belongs to a family of the Phyllo- 

 branchiata that is parallel with the Synaxidea in its relation to the Trichobranchiata, 

 and which it approaches in the form and character of its appendages, with the exception 

 of its having a scaphocerite attached by the second pair of antennas, which the Synaxidea 

 have not. 



1 Dohrn, loc. cit., pi. xv. figs. 1, 2. 



