SH1Z0P0D.E. 61 



the outer are exclusively adapted to swimming and carry 

 the branchia or gills around their basil joint, so that they 

 present us vvith/>er/bc< animals possessed oifourroivs of feet I 

 the inner rows, which arc appropriated to the same pur- 

 poses as the usual members in the true shrimps, are besides 

 wholly unfurnished with chelae or claspers. Our present 

 ignorance of the habitudes of these animals, will not 

 permit our deriving any benefit from characters taken 

 from their mode of breeding, but as in Mysis, it is probable 

 that they do not undergo any metamorphosis. 



The animals with which they are most likely to be 

 confounded, however, are the larvae of the Decapoda, which 

 are temporarily Shizopodse, but may generally be distin- 

 guished by the division of the limb originating from the 

 extremity of the femur or thigh, and shewing no appearance 

 of external branchia ; besides, they are comparatively small 

 and imperfect animals, in which the sub-abdominal fins 

 and tail are never completely developed. From a conside- 

 ration of these characters, the author is induced to exclude 

 Nebalia from the true Shizopodse, which as before hinted, 

 is probably the larva of some crustaceous animal ; at all 

 events, its characters have not hitherto been sufficiently 

 developed by the few Naturalists who have become ac- 

 quainted with it, to enable us to pronounce as to its true 

 situation or affinity. 



No doubt the Shizopodae will receive considerable acces- 

 sions both of genera and species, when more attentionis given 

 to the less conspicuous of the marine Crustacea, for as we 

 have seen, the largest of them scarcely exceed an inch in 

 length, and they appear to be widely distributed, existing 

 from the Equator to the confines of the North Pole, as 

 well in the briny ocean, as in the brackish water of rivers 

 and estuaries. 



