MEMOIR II. 



On the Genus Mi/sis, or Opossum Shrimp. 



The Mysis, or Opossum Shrimp, a Genus instituted by 

 Latreille, appears to have been hitherto noticed by very 

 few Naturalists, and to the bulk of such even as devote 

 . themselves to Zoology alone, they may be said to be 

 wholly unknown ; those few who have had opportuni- 

 ties of observing them, although they have given us some 

 imperfect notion of their structure, have left their singular 

 economy a mere blank, from a practice hitherto much too 

 prevalent, of attending almost solely to the more remark- 

 able differences which distinguish one genus or species 

 from another, as if this was the only object worthy our 

 attention, whilst those circumstances of structure and 

 economy which give a real interest to natural history are 

 either neglected or overlooked. The object of this Memoir 

 therefore, will be to make the Opossum Shrimps more 

 generally and perfectly known, and to display the more 

 remarkable traits in their economy, and may thence be 

 considered as having novelty to recommend it to the atten- 

 tion of the curious ; at the same time it may be observed, 

 that the Marsupial Quadrupeds or Opossums, (although 

 so long and so well known) having lost little of their 

 original interest with the admirers of the works of creation, 

 induces a hope, that a somewhat similar economy displayed 

 for the first time in an animal of a very inferior order, may 

 not be without its attractions ; if in addition to these 

 circumstances we take into account the extraordinunj 

 peculiarities of structure^ which these animals present to 



