CYCLOPOIDEA. IO53 



along the venter. The setae of the antennas very short, not longer 

 than diameter of joints, except at apex, where are two directed for- 

 ward and two backward, which are as long as the last joint. 



Calanus magellanictts. 



Fro7is rotundatus. Cephalothorax 4:-articulatus, justice obtusus. An- 

 termce. anticce corpore breviores, duplo ciirvatce, apicibus fronte valde 

 poster ioribus, articidis quatuor ultimis brevibus, subcequis; setis totisper- 

 brevibus, apicalibus articulo brevioribus, anticis apice remotis, subapi- 

 calibus posticis minutis, anticis obsoletis. Styli caudales perbreves, 

 setis abdominem longitudine fere cequantibus. 



Front rounded. Cephalothorax four-jointed, obtuse before and behind. 

 Anterior antennas shorter than the body, having a double curva- 

 ture, apices behind line of beak ; four terminal joints subequal, setae 

 all very short, those of last joint not longer than joint, two apical 

 reflexed, the anterior near middle of front margin ; the posterior of 

 the subapical joints very short, the anterior obsolete. Caudal 

 stylets very short, setas about as long as abdomen. 



Plate 72, fig. 4 a, side view, enlarged ; . b, position of antennas ; c, 

 extremity of antenna. 



Collected, March 27, 1839, in latitude 52° south, near Patagonia. 



Length, one-twenty-fourth of an inch. Colourless, except some- 

 times a little orange about the centre of the cephalothorax. This 

 species differs from the last in the position of the antennas and their 

 apical and subapical setas. There is a longer set at intervals of 

 three or four joints on the antennas, but none are longer than the joint 

 to which they are attached. The last seven articulations are about 

 equal, and each is shorter than either of the six or seven preceding. 

 The last joint has the anterior setas situated some distance from the 

 apex, and, although no subdividing articulation was distinguished, 

 there is evidently an analogy between this joint, and the terminal in 

 C. comptus and G. rotundatus. In these two species the terminal is as 



264 



