176 THE LARVAL FORMS 



the larval forms of the Crustacea were recognised as such ; before 

 that time they were classed under a genus called Zooea^ hence the 

 term then given is still applied to them in their real character. 



The reason of this obscurity on the part of these peculiar 

 microscopic atoms, for in truth many of them are little more, is 

 not far to seek. Few animals, except our familiar and pugnacious 

 friend the Shore Crab, Carci7ius mccnas, are so extremely difficult 

 to keep in even the best-managed aquarium, as Crabs, Lobsters, 

 Shrimps, Prawns, and Sandhoppers. And if these animals are not 

 favourable for the purpose of observation, under ordinary 

 conditions, it stands to reason, that when laden with mature ova, 

 they are still less likely to live under artificial circumstances ; 

 far more unlikely is it that the tender and fragile Zooea would be 

 able to undergo this natural metamorphosis whilst subjected to 

 unnatural confinement. I suppose that the nearest approach to 

 perfection in the study of the life-history of these creatures exists 

 in the splendid Marine Zoological Station at Naples, and British 

 naturalists will hail with delight the day when something of the 

 kind can be established in some favoured locality on our own 

 shores. 



There is no doubt that the conditions to be aimed at for the 

 successful accomplishment of the object in view are those 

 corresponding exactly with Nature, but unfortunately even the 

 natural conditions under which pretty well half of the British 

 Crustacea undergo their early life are not known. Some of our 

 Crustacea are entirely shore forms, delighting in the zone where 

 the surf breaks with the greatest fury ; others are seldom found 

 except under large stones, and in rock crevices ; others, again, 

 burrow in sand, in mud, or in rock detritus (each material being 

 characteristic of separate and distinct species) ; some live in 

 estuaries, others in ditches of brackish water, in salt marshes, and 

 some swim freely in deep water. As therefore the parents exist 

 under so many different conditions, it is probable also that their 

 Zooea forms enjoy as large a variety of attendant circumstances, 

 but what these circumstances are, in most cases remains a 

 mystery. 



There are, however, a few species which may, with a little 

 care, be studied in confinement, one of the best being our little 



