Freshwater Entomostraca of South America. 237 



Genus Cyclops. 



Sp. 13. C. hrevicornis, Gay. 



" Albescens, antennis primi parls thorace brevioribus." 



Antennae of the first pair much shorter than the thorax : the 

 terminal setae of the lobes of the abdomen as large as the body; 

 eggs in one group on the upper side of the abdomen. Colour 

 rosy white, with patches of yellow on the back; feet white, eggs 

 sea-green. 



Length 



San Carlos de Chiloe. 



I have some doubts whether this is a fresh water species; it is 

 not C. brevicornis, Miiller. 



Family Calanid^. 



Sp. 14. Diaptomus Brasiliensis, n. s. 



Cephalothorax 6-articulatus. Antennae anticae corpore paulo 

 breviores. Antennae secundaj, mandibulee, secundi et tertii 

 nnaxillipedum pares, et quarti primi pedum pares, ut in D. 

 Castore. Pedes postici maris prehensiles. Abdomen maris 

 .'i-faeminae 3-articulatum. 



Long. -^^3^ unc. 



Collected by Mr. Darwin, at Port Desire, in Patagonia. It 

 inhabits fresh water. 



The anterior antennae consist, as usual, of about twenty-four 

 segments ; the right antenna of the male is prehensile, and the 

 hinge joint is situated between the fifth and sixth segments, count- 

 ing from the apex. The sixth, seventh, eighth, ninth, tenth seg- 

 ments, are slightly swollen, and contain the strong muscle which 

 closes the hinge joint. I believe that it is opened again by its 

 own elasticity, as I could not see any muscle for that purpose. 

 The fifth, sixth and seventh segments bear each a large spine, 

 which is pressed close to the antenna itself. The arrangement of 

 the hairs is very similar to that which I have described in the 

 , Ann. and Mag. of Nat. Hist, for September, 1853, as occurring 



