94 



CRUSTACEA — CIRRIPEDIA 



very much in the state characteristic of the Cypris larvae of other 

 Cirripedes, being furnished with two terminal hooks by which 

 attachment is effected. The thoracic appendages, of which there 

 are the normal number six, are reduced flabellate structures, and 

 the abdomen forms an indefinitely segmented lolie of consider- 

 able size. 



The animal appears to be in an arrested state of development, 

 and so retains some of the characteristics of the Cypris larvae, but 

 it is very doubtfid how far these characters can be considered 

 primitive. 



Other forms are Btnilrogaster astericola on Echinoderms, 

 and t^ynagoga mira on the "Black Coral," Tarantiimtlic& larix, at 

 Naples. 



Sub-Order 5. Apoda. 



Darwin described a small liermaphrodito parasite in the mantle 



.p chamber of Alepas cor- 

 nnta from Saint Vin- 

 cent, West Indies, 

 which he named Pro- 

 tcole-pas hivi^icta. 



Tlie body (Fig. 

 65) is distinctly seg- 

 mented into eleven 

 somites, the last three 

 of which are supposed 

 to belong to the ab- 

 domen ; there are no 

 appendages except the 

 antennae by whicli 

 fixation is effected. 



Fig. 65. — Proteolepas hivincta, x 26. A 

 a, b, 1st and 2ii(l alidomiiial segments 



Antennae 

 0, ovary 



mnvSV ^' t^l^- •' 1-8' tl^^racic segments. (After The mOUth-parts are of 



normal constitution. 

 This animal lias not been found again since Darwin's dis- 

 covery, but Hansen^ descriljes a number of peculiar Nauplius 

 larvae taken in the plankton of various regions, which he 

 argues probal)ly belong to members of this group. A wide field 

 of work is offered in attempting to find tlie adults into which 

 various larvae grow. 



^ Plankton Expedition, ii. G. d. ]899. 



