208 POPULAR HISTORY OF THE AQUARIUM. 



maturity. After first moulting, the body is seen plainly 

 divided into two parts, the anterior of which is furnished 

 with three pairs of swimming-feet, and the posterior with 

 two pairs of swimming-feet. No doubt there are a good 

 many stages of development to go through before they as- 

 sume the mature form, but it has not yet been possible to 

 follow them out. It is not the least curious part of the 

 history of these singular-looking animals, that the young 

 should thus stand on a higher stage of development than 

 the mother ; and that their progress from youth to ma- 

 turity should be in the directly opposite ratio to that of 

 all the other Crustacea. At what period of their existence 

 they fasten themselves upon their prey is at present un- 

 known ; but no sooner apparently does this happen than the 

 eye disappears, and the feet either disappear also, or are 

 transformed into other organs."" 



LeRNEONEMA SPRATTiE 



Is a long cyHndrical body, with two posterior appendages 

 and a narrow neck. It has the head shaped like the head 

 of a harpoon, on each side of which is a hook turned back- 

 wards. When the creature attaches itself to the head, near 

 the eye, of the Sprat, it buries its head in the substance of 



