94 



CRUSTACEA CIRRIPEDIA 



CHAP. 



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 fiabellate structures, and 

 the abdomen forms an indefinitely segmented lobe 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 doubtful how far these characters can he considered 

 primitive. 



Other forms are Dendroyaster astericola on Echinodenns, 

 and Synagoga mira on the " Black Coral," Parantipathes larix, at 

 Naples. 



Sub-Order 5. Apoda. 



Darwin described a small hermaphrodite parasite in the mantle 



chamber of Alepas cor- 

 nuta from Saint Yin- 

 /J4 cent ' West Indies, 

 & JPffl which he named Pro- 

 tcolepas l)iri'iic/(i. 



The 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 which 



rni. oo. 7V/,/,Y;/,y/r>.x In n.iicta, x 26. A, Antennae; . _ J 



, b, 1st and L'nd abdominal segments ; <>. ovary ; fixation is effected. 

 /', penis; T, tel.son ; 1-8, thoracic segments. (After The mouth-part s are of 

 Darwin.) 



normal constitution. 



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

 covery, but ITansen 1 describes a number of peculiar Nauplius 

 larvae taken in the plankton of various regions, which he 

 argues probably belong to members of this group. A wide field 

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

 various larvae grow. 



1 Plankton Expedition, ii. G. d. 1899. 



