CIRRIPEDIA. 293 



organ, developed from the vertical surface of the apex of the abdomen, 

 but not, according to Darwin, the modified homologue of the ab- 

 domen. 



Class EPIZOA. 



Body, chitinous, vermiform, subarticulated, not always symmetrical; 

 with antennae and articulated limbs terminated either by suckers, 

 hooks, or bristles. Vascular system diffused: white blood. No re- 

 spiratory organs. Dioecious. Males small or rudimentary : females 

 with external pendent ovisacs. Metagenesis resulting in a usually 

 permanent parasitic attachment on the bodies of fishes. 



The class is subdivided according to the mode of that attachment. 



Order I. Cephaluna.* 



Attachment by cephalic processes, sometimes numerous and com- 

 plex. 



Genera Peniculus, Lerncea, Chondr acanthus ^ LerncBocera^ Penella. 



Order II. Brachiuna. 



Attachment by a suctorial disc at the confluent extremities of the 

 last pair of thoracic limbs. 



Genera Achtheres, Tracheliastes, Brachiella, LerncBopoda, Ancho- 

 rella. 



Order III. Onchuna. 



Attachment by hooks at the free extremities of the first pair of 

 thoracic limbs. 



Genera Dichelestium, Lamproglenay Ergasilus, Nicothoe. 



Class CIRRIPEDIA.t 



Body, chitinous or chitino-testaceous, subarticulated, mostly sym- 

 metrical, with aborted antennse and eyes. Mouth, prominent, com- 

 posed of a labrum, palpi, two mandibles, and two pairs of maxillse. 

 Thorax, attached to the sternal internal surface of the carapace, with 

 six pairs of multiarticulate, biramous, setigerous limbs. Abdomen, 

 rudimentary ; vascular system diffused : white blood. Branchiae, 

 when present, attached to the inferior lateral part of the surface. 

 Most are hermaphrodite ; a few have minute rudimentary male indi- 

 viduals parasitically attached to the females. Penis, proboscidiform, 



* K€(pa\ri, the head, and ew-rj, a bed or last resting-place, in the plural 

 " anchors." 



t In the characters and subdivision of this class I have followed Darwin. 



u 3 



