EPICARIDA LIFE-HISTORY OF DANALIA 



131 



Fig. 86. — Inachus mauritanicus, 9, xl, carrying 

 two SaccuUna negUda {a, b), and a Bcmalia 

 curvata (c), the latter bearing two dwarf males. 



which is itself parasitic on the spider-crab, Inachus mauritanicus, 

 at Naples. The adult Danalia is a mere curved bag full of eggs 

 or developing embryos, and without any other recognisable organs 

 except two pairs of sper- 

 mathecae upon the ventral 

 surface where the sper- 

 matozoa derived from the 

 larval males are stored. 



In Fig. 86 is repre- 

 sented a female of Inachus 

 mauritanicus which carried 

 upon it two Sacculinae and 

 a Danalia curvata, and 

 upon the latter are seen 

 two minute larval males 

 in the act of fertilising the 

 adult Danalia. The eggs develop into the Epicaridian stage, 

 after which the larva passes into the Cryptoniscus stage (Fig. 87). 

 In this larval form the segments are clearly delimited ; the only 

 mouth-parts present are the mandibles, but there are seven pairs 

 of thoracic limbs and the full number of 

 pleopods. This Cryptoniscus stage is found in 

 all the Epicarida, and only differs in detail in 

 the various families. 



In the Cryptoniscina the Cryptoniscus larva 

 is the male, and at this stage possesses a pair 

 of large testes in the thorax. The ovaries are 

 also present at this stage as very small bodies 

 applied to the anterior ends of the testes. The 

 larval males in this state seek out adult fixed 

 Danaliae and fertilise them ; and, when this is 

 accomplished, they themselves become fixed to 

 the host and begin to develop into the adult 

 Fig. 87.— Ventral view female condition. The limbs are all lost, and 

 of Cryptoniscus q^j; gf ^j^g niQuth grows a long proboscis (Fig. 



larva of Danalia ° ° -^ i- i 



cwrmto, (5 , X 25. 88, P ), which penetrates the tissues 01 the 

 host. The ovaries begin to grow, and a re- 

 markable process of absorption in the testes takes place. These 

 organs, when fixation occurs, are never empty of spermatozoa, 

 and are frequently crammed with them. After fixation some 



