1058 CRUSTACEA. 



The antennae of the second pair are short, and so also their seta?, and 

 the setae of the following organs. 



Calanus stylifer. 



Irons truncatus. Ceplialothorax curtus, postich dbdomine valde latior et 

 elongate acutus, 5-articulatus, segmento ultimo brevissimo. Antennae 

 anticce duplo paulidum curvatce, apieibus fronte non posterioribus ; setis 

 perbrevibus, apicalibus et penultimd posticd fere articuli longitudine, 

 penultimd anticd et antepenultimis brevissimis. Styli caudales ienues, 

 fere abdominis longitudine, recti, paralleli, setis non longioribus, una 

 valde externa. 



Front truncate. Ceplialothorax short, behind much broader than 

 abdomen, posterior angles acutely prolonged, five-jointed, the last 

 segment very short. Anterior antennae slightly doubly curved, 

 apices a little in advance of line of beak; setae very short, the 

 apical and posterior penult nearly as long as joint, the anterior 

 penult and antepenult very short. Abdomen three-jointed. Caudal 

 stylets slender, not as long as abdomen, straight, parallel, seta? 

 hardly longer than stylets, four apical, and one which is somewhat 

 shorter, proceeding from the middle of the exterior side. 



Plate 72, fig. 9, view, enlarged. 



Obtained in the Atlantic, off the harbour of Rio Janeiro, in latitude 

 23°-24° south, longitude 41°-43° west, November 19, 1838, and 

 January 9, 1839. 



Length, one-twelfth of an inch. Colour, a little yellowish in front, 

 with dirty brown along the centre, arising from the alimentary mate- 

 rial within. The cephalothorax is not longer than two and a half 

 times its breadth, and the prolonged posterior angles are wide apart 

 and distant from the sides of the abdomen. There is a short promi- 

 nence near the centre of the back, seen in a lateral view. The first 

 joint of the abdomen is much longer than either of the others. The 

 fifth or rudimentary pair of natatories is not half the length of the 

 preceding ; it is without setae, and very slender. The last three or four 



