4 MEMOIR I. 



The animals of the supposed Genus Zoea, have heen 

 hitherto little known from their small size, transparency, 

 and the other circumstances above alluded to. Slabber, 

 Bosc and Cranch, are the only Naturalists who have had 

 the good fortune to observe them ; to these may be added 

 the author, who in towing for luminous animals, during a 

 voyage from the Mauritius in 1816, discovered the species 

 figured in Plate I. fig. 2, and fig. 4, a. b. without having it in 

 his poAver to throw any new light upon their nature or 

 structure : great variety of subjects, and the difficulty of 

 pursuing microscopical dissections of minute animals on so 

 turbulent an element, having prevented this being followed 

 up at the moment, and having subsequently lost these 

 specimens, we might have remained for an indefinite period 

 without the knowledge of their real nature, the profusion 

 in which they occur in our own seas, their variety, and 

 the peculiarities of their structure, had not he continued 

 to use the muslin towing net, for the detection of minute 

 marine animals, since his return to Europe ; many, and 

 important, have been the results of this simple procedure, 

 but none attended with greater surprise, than the vast 

 profusion of the animals of Zoea discovered on our coasts 

 and in our bays and estuaries, the novel and curious 

 history of which, it is intended to give in this and subse- 

 quent memoirs. 



Slabber in a Dutch Work entitled " Natural Amusements 

 and Microscopical Observations" published at Harlem in 

 c 1778, has given us a description and figure of the species 

 which has been since designated Zoea ^azm«,PlateI.fig.l,rt 

 (in outline and without adventitious groups of a vorticella) 

 several of these were taken at sea, July 24, 1768. From 

 the observers of that period, any very exact analysis of 

 such an animal was not to be expected, its whole length 

 being but \\ line ; he describes it as of a greenish colour, 

 the tail paler, the corselet with a long frontal and dorsal 

 spine, the fourth joint of the tail with a projecting spine 



