Mr. J. D. Dana on some genera of Cyclopacea. 185 



and smaller than the first pair of legs. [I am not satisfied that 

 these specimens are not the female of the Coryccei.'] 



Genns 3. Sapphirina, Thompson. Body much-depressed; 

 antennae as in Corycaus ; abdomen 5- or 6-jointed, the basal joint 

 in the female abruptly narrower than the thorax, and having a 

 pair of short appendages ; external ovaries two. 



Family 5. Miracid^e. Antennae as in Setella ; external ovary 

 single. 



Genus 1. Miracia, Dana. Body not depressed, nearly as in 

 the A?pactida; the abdomen 5- or 6-jointed and not abruptly 

 narrower than the thorax ; anterior antennae nearly as in Setella, 

 with a short appendage near the middle ; second pair of antennae 

 terminating in a few moveable setae ; beak with two cultriform 

 appendages ; first pair of legs subcheliform. 



The distinctions in the above genera rest to a considerable ex- 

 tent upon the use of different organs for grasping in the union 

 of the sexes. In Cyclops and Arpactus, both anterior antennae 

 of the male are subcheliform for this purpose ; in Pontella and 

 Candacia the right antenna and right posterior thoracic leg are 

 thus modified in the male ; in Euchirus both posterior thoracic 

 legs are very much elongated ; in Calanus the first pair of legs 

 are long, and have an outward lateral motion for the purpose ; 

 in Corycams the second pair of antennae subserve this end, and 

 in Antaria the first pair of legs are large and subcheliform ; in 

 Setella the same end appears to be secured by the first pair of 

 natatories. 



The genera of Calanidce differ also in the relative development 

 of the maxillipeds and first pair of legs. In Pontella, Acartia 

 and Scribella the maxillipeds are largest. In Pontella and Acar- 

 tia they are straight, with long setulose setae directed forward so 

 as to form a kind of scoop-net. In Scribella they are flexed like 

 the letter L. In Calanus, Euchirus and Candacia the first pair 

 of legs are larger than the maxillipeds ; in Calanus they are long 

 and spread outward laterally ; in Euchirus they are thrown for- 

 ward in the line of the body, and are flexed like the letter \/\ ; 

 and in Candacia they have nearly a similar position, but have the 

 extremity flexed towards the head instead of away from it. 



The maxillipeds may always be distinguished from the first 

 pair of legs by the setae, which are setulose in the former and 

 naked in the latter*. 



* This article, for the communication of which we are indebted to the 

 author, has also been published in Silliman's American Journal for March 

 1846.— Ed. 



