456 Pjof. K. Grobben on the Genealogy and 



modification of the process must not be rejected, especially 

 with reference to tlie position of the compound eyes in the 

 larvffi of Cirripedes. 



From what has been stated as to the Copepods the following 

 conclusions may be drawn with regard to their affinity to the 

 Euphyllopods : — Among the Copepods the Branchiura are in 

 the first place to be considered as the group which in general 

 have preserved what are phylogenetically more ancient 

 characters, although in many respects, as in the formation of 

 the cephalic appendages, secondary modifications have set in 

 owing to the parasitic mode of nutrition. The Branchiura 

 consequently represent a remnant of a primitive Archi- 

 copepod group. The isolated position occupied by the 

 Branchiura among the Copepoda, as well as the small number 

 of genera {Argulus and Gyropeltis) and species by which these 

 animals are represented at the present day, are in accordance 

 with this conception. In this sense, too, in the genealogical 

 tree of the Entomostraca, to which reference has already 

 several times been made, Glaus has made the root of the 

 Branchiuran twig arise from the bottom of the Gopepod 

 branch. 



This Archicopepod group had, judging from the structure 

 of Argulus^ the hahitus of Ajms ; consequently, according to 

 my theory it is to be derived from that Archiphyllopod 

 series which led to the existing Apodidse, the character of 

 which it already bore. Its branching-off from the Apus- 

 series, however, took place at a period when the forms 

 belonging to this series possessed the biramous swimming- 

 foot-antenna, the mandibular foot, and foliaceous-foot-shaped 

 maxillfe, and accordingly lies deep down on the stem of the 

 Apodiform Archiphyllopods. To judge from the peculiarities 

 of the lateral eye in Argulus, the sinking-in and covering-over 

 of the compound lateral eyes were processes which already 

 occurred in these ancestors of Apus from which the Copepods 

 sprang. There is also no need to point out specially that the 

 Copepods too, like the Ostracods, have proceeded from a much 

 more extensively segmented form through reduction of the 

 segments of the body. 



The Cieripedia. 



A consideration of the adult Cirripedes furnishes but very 

 few points of importance for the answering of the question as 

 to their origin. This is moreover to be accounted for by the 

 altogether exceptional mode of the attachment of these 

 animals by the cephalic end, and the changes in the develop- 



