2Q-7g CRUSTACEA. 



Collected in the Sooloo Archipelago, February 2, 1842 ; also in Straits 

 Of Banca, March 2, 1842. 



Length, one-eighth of an inch. Colour, a shade of rose, with red 

 blotches ; another specimen with a tinge of greenish yellow. 



Resembles the two preceding, but differs from both in the long seta 

 to third joint of antenna, directed straight forward, and the more 

 widely spread caudal setae. The abdomen is four-jointed, the first 

 segment oblong. In some young individuals, the prominent posterior 

 angles of thorax were much shorter than in the figure, and only subacute. 

 The penult is the shortest of the five terminal joints of the antennae; 

 the long posterior subapical setae about equal the last five joints, the 

 anterior antepenult is about half as long as joint, apical less than 

 length of joint. Caudal stylets not longer than broad. 



From the setuligerus it differs in having the cephalothorax behind 

 acute. 



J5. Setae cauddles 2dse longissimte. Frons sive obtusus sive triangulato-acutus ; rostro 

 elongate furcato, brachiis setiformibus. 



Calanus gracilis. 



Gracilis. Frons rotundatus. Cephalothorax elongatus, 5-articulatus, 

 postich obtusus, segmentis 4 posticis subcequis, ultimo par ce breviore. An-- 

 tennce anticce sesqui corpore longiores, recta?, 160° inter sese divarv- 

 catce; setis brevibus, duabus posticis subapicalibus longis, apicalibus et 

 anticis subapicalibus brevibus. Abdomen curtum, i-articulatum. 

 Styli caudales breves, setis secundis dimidio corporis longioiibus. 



Slender. Front rounded. Cephalothorax elongate, obtuse behind, 

 five-jointed, four posterior segments subequal, the last somewhat 

 shorter than the others. Anterior antennae more than one and a 

 half times the length of the body, straight, slightly curved at base, 

 the two diverging at an angle of 160°; first joint short, second a 

 little oblong, penult abbreviate; setae short, two posterior subapical 

 long, apical and anterior subapical short. Abdomen short, four- 

 jointed. Caudal stylets short, second seta much longer than half 

 the body, the others of moderate length. 



