196 Miscellaneous. 



with tlic head directed foi'wards towards the opening of the mouth 

 of the fish. Usually one male keeps beside the female ; sometimes 

 several males are met with near a single female. 



The moults take place in all these Crustacea in a peculiar man- 

 ner. The skin first of all qnits the hinder part of the body, the 

 animal remaining strongly attached by the front legs ; the anterior 

 part of the body is disengaged in its turn in the same manner, the 

 animal being then attached by the new claws of the hinder feet. 

 This mode of changing the skin is an absolutely necessary condition 

 for the copulation. In fact, the act would become impossible if 

 the oviferous pouch of the female were formed at once beneath all 

 the segments of the body, thus stopping the sexual orifices, which 

 are formed at the same time towards the sides of the ventral arch 

 of the fifth segment. Eut the oviferous pouch, half-formed after 

 the moult of the posterior part of the body, having as yet only three 

 lamellfc, which are attached to the last three segments of the body, 

 remains broadly open in front ; and the male can easily make his 

 way into it. After copulation, the female, changing the skin of her 

 anterior part, at the same time completes the oviferous pouch with 

 the lamelhe belonging to that region of the body. It is to be re- 

 marked that the anterior lamella; of the oviferous pouch cover the 

 jaw-feet and often the mouth itself — an arrangement which proves 

 that the female now takes scarcely any more nourishment. The 

 lamella? being directed forward, it is in this direction beneath the 

 head that the young issue from the oviferous pouch after their first 

 moult. The female remaining attached and motionless during the 

 deposition of the ova, dies flaccid and empty after the escape of the 

 young. 



In many of these Criistaceans, especially in the errant suctorial 

 CymothoadaD, the young are very large in proportion to the adult 

 animal, and, to make up for this, are not very numerous ; in others, 

 on the contrary, the young, to the number of a couple of thousand, 

 are of extreme miniiteness. As a matter of course, these proportions 

 are in direct relation with the greater or less difficulties which the 

 young must encounter during their evolutive life, according to the 

 mode of life of the different fishes to ■which they attach themselves. 

 In the young the configuration and the relative size of the head, 

 antennae, eyes, and the last segment of the tail and its appendages, 

 and the number, form, and distribution of the pigment spots, present 

 a multitude of differences according to the species. The claws, 

 which arc always simple and but slightly curved before the first 

 moult, often become strongly serrate after this moult — a structure 

 Avhich is gradually lost during the following moults. All these 

 differences during youth frequently become a great assistance in the 

 specific distinction of the adult animals, especially when the latter, 

 as is the case in a great proportion of the parasitic Cymothoadfe, 

 have undergone a retrograde metamorphosis as they increased in 

 age. The females, converted into a more or less shapeless ovife- 

 rous sac, lose to a great extent the symmetry and the definite form 

 which distinguished their different appendages during the natatory 

 Ptage of their life. Even in the errant suctorial CHmothoadae the 



