214 CLASS CRUSTACEA. 



But a single genus can be found of them, to which, from 

 ancient usage, we shall preserve the name of 



Cyamus, Latr. 



Some, FiLiFORMA, Latr., have the body long and very 

 slender, and linear, with the segments longitudinal. The feet 

 equally elongated and slender, and the stem of the antennae 

 composed of many small articulations. 



Leptomera, Lai. Proto, Leach, 



Have fourteen feet (the two annexed to the head comprised) 

 complete, and in a contimied series. 



In some, as in our Leptomera proper {Gammariis peda- 

 tiis, Mull.) all the feet, with the exception of the anterior two, 

 have a vesiculary body at their base. In others, as the Proto' 

 of Leach {Cancer pedatus, Montagu), these appendages are 

 proper only to the second feet and the four following. 



Naupredia, Latr., 



Have but ten feet, all in a continued series, the second and 

 the two following pair have at their base a vesicular body. 



Caprella, Lamarck, 



Have likewise but ten feet, but in an interrupted series, com- 

 mencing inclusively at the second segment, not counting the 

 head. This segment and the following each present the vesi- 

 cular bodies, and are totally deprived of feet. {Squilla lohata, 

 Muller.) 



The other Isemodipods, Ovalia, Lat., have the body oval, 

 with the segments transverse. The stem of the antenna? ap- 

 pears to be inarticulate. The feet are short, or but little elon- 

 gated ; those of the second and third segments are imperfect, 

 and terminated by a long cylindrical articulation, and without 



