Report on Larval Crabs. 11 



The new branch of the antenna is about as long as the smallei^ of the two 

 original branches. The jointed branch without its terminal spine is longer 

 than the new branch ; with its terminal spine- it is a little shorter than the 

 serrated branch. 



The exopodites of the first and second maxillipedes had ten setae. 



The pleopods were prominent (fig. 30). The drawing of the abdomen 

 was made from a III. Zoea which had cast off the integument of the 

 abdomen, but not that of the thorax. The newly-exposed abdomen 

 appeared normal, but the telson had not yet swollen out. 



The telson of this stage (fig. 48) shows an additional pair of hairs in the 

 fork. The kwo which appeared in III. Zoea have increased in length. 



A TV. Zoea cast into a V. Zoea (fig. 34a). 



V. Zoea, fig. 34a; Abdomen, fig. 40; Telson, fig. 38; Antenna, fig. 34. 



The first maxillipede had eleven setae on the exopodite of both sides. 

 The second maxillipede had twelve setae on one side and eleven on the 

 other. In the case of the twelve setse, two were situated a little way 

 along the exopodite, separated from the rest of the setfe by an interval. 

 On the other side, one of the eleven setae was separated from the rest by 

 an interval. 



This stage, except in being bigger, generally resembles the last. The 

 pereiopods are now almost full-sized. 



The new branch of the antenna is as long as, or greater than, the original 

 sei-rated branch (fig. 34). The jointed branch with its spine is nearly as 

 long as the serrated branch ; without its terminal spine it is two-thirds the 

 length of the serrated bi-anch. 



Five hairs were observed on one side of the dorsal edge of the dorsal 

 spine, and four hairs on the other. I did not make out the hair on the 

 carapace at the base of the dorsal spine. Eight sparsely plumose setae 

 were noticed on the free edge of the carapace. 



The abdomen (fig. 40) resembles the last stage, except that the pleopods 

 and uropods are much larger. 



The telson (fig.- 38) closely resembles that of the last stage. Some of the 

 spines in the specimen drawn had been broken off. 



The new hairs that appear in the fork of the telson in the III. and IV. 

 Zoea, and which continue in the Y. Zoea, are, it may be inferred, correlated 

 to new conditions in the cephalic appendages, which require extra armature 

 in the telson for its work in effecting the ecdysis. 



A Y. Zoea cast into a Megalops. 



Megcdops, figs. 11, 17. 



This stage has a comparatively long rostral spine and a stout dorsal 

 spine. All the appendages are functional, the pleopods being plumose. 

 The spines are absent from the abdominal segments. The antenna has 

 four (or five) terminal stiff cilia. There are comparatively few hairs on 

 the dorsal surface ; they are generally small. 



The first, second, third, and fourth pereiopods bear large hooks (fig. 17). 

 That of the chela is on the ischiopodite ; in the other three the hook is 

 on the coxopodite joint. The fifth pereiopod is without a hook ; the 

 dactyl of this pereiopod has the three long curved spines characteristic 

 of the genus Portunus. 



Fig. 1 7 was drawn from the cast integument of a Megalops. 



A Megalops cast into a first young stage. 



First Young Stage, fig. 29. 

 The margin of the rostrum is serrated. 



