CYPRIDiE. 145 



three or four terminating ones of which arise several 

 pretty long filaments, which vary in number in the dif- 

 ferent species. Whenever the animal moves, it invariably 

 puts these organs into rapid motion, dilating and bringing 

 together again the long filaments, aiid waving them to 

 and fro with great rapidity. They are thus considered 

 by Miiller and Straus to act as true fins, and to be the 

 principal organs of progressive motion. Jmine, however, 

 says that, from their position in the anterior part of the 

 body, and from their motions being thus confined by the 

 opening of the shell, they cannot be considered as acting 

 the part of true fins, and that their use in progressive 

 motion is by no means equal to that of the inferior an- 

 tennae, called by him the anterior feet. In the larger 

 species we see these filaments to be beautifully plumose, 

 a circumstance which has never been pointed out by any 

 of the various authors who have written upon the genus, 

 and which strengthens Latreille's suggestion that they 

 may act as respu'atory organs, as well as the branchial 

 plates of the jaws. The inferior, or second pair of antennas 

 (t. XVIII, f. I c), arise immediately beneath the others; 

 they are very strong, and resemble in appearance feet as 

 much as antennae : indeed, they have almost invariably 

 been considered and described as the first pair of feet. 

 Their position, however, in front of the mouth and organs 

 of mastication, as in the other genera of Entomostraca, 

 and their resemblance to the inferior antennae of the 

 Cyclopidae, warrant us, along with M. Edwards, in con- 

 sidering them as antennae. They consist each of five 

 articulations:* two belonging to the basilar portion, short, 

 and directed downwards ; a third, longer, directed for- 

 wards ; and two terminating joints, the first of which, in 

 most of the species, gives off at its lower extremity a 

 bundle of setae, which are frequently plumose ; and the 

 last being terminated by several tolerably strong hooked 

 spines or claws. This pair of antennae, therefore, by 



* Jurine says eight. 



10 



