CRUSTACEA 277 



is taken out of the water. They are also frequently 

 captured in the dredge, or on shore, when not attached to 

 fishes. 



There is some room for doubt whether the male larvae are 

 similar to the female. If so, then the larval male has the 

 three posterior pereion segments united and swollen, and 

 then when he casts his cuticle and changes to the adult form 

 these three segments appear free and reduced in breadth. 

 This is stated by Hesse to be actually the case ; that observer 

 maintains that all larvae have the form originally named 

 Praniza. Sars also states that he has witnessed the trans- 

 formation of the Praniza larva into the adult male or Anceus 

 form. 



Bate and Westwood, on the other hand, state that the 

 sexes could be distinguished in the larvae, though they do 

 not state what the distinction was. When the larvae leave 

 the brood-pouch all the segments of the pereion are distinct. 

 The mother appears to die after the escape of the young 

 from the pouch. 



On the whole, the evidence shows that the difference 

 between males and females, if any, in the larvae must be 

 very slight, and that both lead the same parasitic but not 

 sedentary existence. The great difference in the adults 

 must therefore be attributed entirely to a difference in habits 

 and functions confined to this stage of life. The fusion and 

 distension of the three posterior segments of the pereion in 

 the larvae must be attributed to the distension of this part 

 by the blood on which the animal feeds, the mode of life 

 resembling that of a leech. In the adult male these segments 

 return to the original free condition, while in the adult 

 female the same portion of the body is still distended by the 

 mass of large ova which develop there. The shape and size 

 of the cephalon in the male is entirely due to the great 

 muscles which move the enlarged mandibles, and, as was 



