r32 Af>'' ■£• Lovett. 



current of water through them. An ovum, when newly 

 deposited, is found to consist of a colourless transparent 

 envelope full of transparent fluid of a tint varying as we have 

 seen in different species. This envelope of membrane is 

 continued in a strong viscid ligature which is apparently 

 twisted, and as these ligatures unite they become stronger and 

 thicker, ultimately forming the stout peduncle which attaches 

 them to the basal joint of the swimmeret, and supports the 

 whole group. 



The first indication of the development of the egg is 

 the granular appearance that the yelk assumes, and its 

 separation from the envelope ; gradually the outline of the 

 enclosed Zooea becomes defined, and the yelk is then enclosed 

 in the large cephalo-thorax. 



At this stage tne most prominent feature is the eye 

 which gives the ova a most remarkable speckled appearance 

 even when seen without the aid of the Microscope. 



In the mature &gg, the abdomen of the Zooea is closely 

 folded on the sternum of the cephalo-thorax, and the limbs 

 lie in close contact with the antennae, antenules and 

 mouth organs. When the Zooea leaves the tgg the envelope 

 of the latter is simply a collapsed and crumbled membrane, 

 and in this respect resembles the ova of many of the 

 Lepidoptera. 



The larval, or zooea form of the stalk-eyed Crustacea are 

 most remarkable in structure, and until comparatively recently 

 were regarded as a distinct order of animals, or rather as allied 

 to the Entomostraca. When first hatched their eyes are 

 sessile, their cephalo-thorax large, more or less round in form, 

 and, in many genera, armed with large curved spines. The 

 abdominal segments are long, simple, and terminate in a 

 remarkable filamentous tail (the Zocea of Lithodes maia is 

 particularly curious in this respect, its tail development 

 presenting a broad fan-shaped expanse of branching filaments 

 of most delicate and beautiful structure). The swimming feet 

 are absent, but the ambulatory feet are developed into limbs 

 armed with setae, thus supplying the necessary natatory 

 organs ; as the true swimmerets appear, these others gradually 

 assume the structure of walking appendages. 



These larval forms, in successive moults, assume the 

 eyes fixed on peduncles and the other characteristics of the 

 fully developed animal. 



It is very remarkable that, unlike the Lepidoptera and 

 Coleoptera, the Crustacea arrive at their final stage before they 

 can be said to have grown at all. If we take any of the insects 

 we find that all the growing takes place during the larval state; 

 whereas, if we take as an example, the common edible crab, 



