

CYCLOPOIDEA. 



1063 



days afterwards in the harbour of Rio. It appears to be the same 

 species; but it differs in having but two joints to the abdomen, the 

 first quite short, the second oblong; and in having the subapical pos- 

 terior setae more nearly equal than in the preceding. Whether these 

 differences are owing to a difference of sex, age, or species, I am 

 unable to decide. 2 b, represents the extremity of the superior an- 

 tenna; 2 c, the posterior antenna; 2 d, leg of first pair. 



Calanus medius. 



Frons rotundatus. Cephalothorax posticd obtusus. Antennae anticce 

 cephalothorace paulo longiores, duplo curvatce, apicibus fronte poste- 

 rioribits; setis perbrevibus, 4-5 remotis longioribus, posticd apicali et 

 anticd penidtimd largd articuli longitudine, posticd penultirnd paulo 

 breviore, posticd antepemdtimd duplo longiore. Styli caudales breves, 

 setis appressis, abdomine brevioribus. 



Front rounded. Cephalothorax obtuse behind. Anterior antennae a 

 little longer than cephalothorax, doubly curved, tips behind line of 

 beak, setae very short, four or five at intervals longer, posterior 

 apical and anterior penult fully as long as joint to which attached, 

 posterior penult a little shorter, posterior antepenult twice longer 

 than the apical. Caudal stylets short, setae shorter than abdomen, 

 straight and not spreading. 



Plate 73, fig. 3 a, animal, enlarged ; b, extremity of antenna. 



Collected in the Pacific, latitude 44° north, longitude 153° west, 

 July 6, 1841. 



r 



Length, one-sixteenth of an inch. 



This species is near the preceding. From the third joint of the 

 antennae there is a seta extending forward, which is as long as three 

 diameters of the joint. The antepenult joint has no distinct anterior 

 seta, or only a very short one ; the praeantepenult has a very short pos- 

 terior seta. At the apex, there are, besides the posterior apical, one 

 directed outward and two obliquely forward. Abdomen in specimen 

 4-jointed; first abdominal segment the longest. The caudal stylets 



