MYSIS. 141 



Boothia depend in a great measure for their winter store of 

 provisions. It is also the chief food of the whale, by which 

 such a prodigious quantity of fat is produced in the body of 

 that immense animal. During the summer they assemble 

 in vast myriads at the mouths of rivers, but in the winter 

 they are more generally distributed along the whole line of 

 coast, and, together with the Argonauta arctica, are to be 

 seen in every crack that opens with the tide, even at the 

 coldest period of the year." 



Fam. MFSIDIDjE, M. Edw. Opossum Shkimps. 

 All the legs of the same form, and fitted for swimming. 

 Thorax thick and compressed on the sides. Carapace with 

 the margins folded under at the base of the legs, and 

 nearly concealing all the thoracic ring. Abdomen much 

 developed ; there are six or eight pairs of thoracic legs, 

 which are provided with a well- developed palpus, which 

 makes them appear double. 



Gen. 48. MYSIS, Zatr.— (Plate IX. fig. 4.) 



No thoracic branchise. One or two pairs of foot-jaws ; 

 hind feet complete. False abdominal feet very small, and 

 without branchial appendages, the last two feet furnished 



