EPJZOA. 133 



minute ganglia in the neighbourhood of the head ; at least, the 

 perfect structure of the oral apparatus, and the developement 

 of the limbs, would seem to indicate such a type of structure. 



(174.) The generative organs in the female Adheres consist of 

 two parts ; the ovaria, wherein the eggs are formed, contained in 

 the abdominal cavity (Jig. 53, d, d), and of two external append- 

 ages, or egg-sacs (Jig. 53,/,/), which are attached to the pos- 

 terior extremity of the body for the purpose of containing the 

 eggs until their complete developement is accomplished ; this ar- 

 rangement we shall again have an opportunity of examining in 

 the entomostracous crustaceans. 



The internal ovaria (Jig- 55, /), when distended with ova, 

 occupy a great part of the cavity of the abdomen, and present a 

 racemose appearance ; but when empty, as represented upon the 

 opposite side of the same figure (e), each is found to be a simple 

 blind canal, with sacculated walls, opening externally by an ori- 

 fice (g, g), through which the ova are expelled into the egg-sacs, 

 where their developement is completed. 



(175.) It would seem that, even when the eggs are hatched, the 

 excluded young are far from having attained their perfect or adult 

 form ; but undergo, at least, two preparatory changes or metamor- 

 phoses, during which they become possessed of external organs 

 so totally different from those they were furnished with on leaving 

 the egg, that it would be difficult to imagine them to be merely 

 different states of existence through which the same animal passes. 



On first quitting the egg, the young Adheres is in fact by no 

 means adapted to the parasitical life to which it is subsequently 

 destined ; possessing no organs of prehension like those of the adult, 

 but merely two pairs of swimming-feet, each armed with a brush of 

 minute hairs, and calculated to propel it through the water. Be- 

 fore, however, the first change is effected, another set of feet may 

 be perceived through the transparent external covering, encased 

 as it were in the first ; when these are completely formed, the 

 original skin falls off, displaying, in addition to two new pairs 

 of swimming-feet, three pairs adapted to prehension ; and it is 

 only when the second set of feet is thrown off in a similar manner 

 that the animal assumes its perfect or mature form. 



(176.) The affinities between the more highly organized EPIZOA 

 and the CRUSTACEA are evidently very strong ; yet, independently 

 of the different character of the nervous system, there is another 

 important distinction between them, derived from their compara- 



