-QQ4 CRUSTACEA. 



served by the author with a bag of eggs attached to the female abdo- 

 men, it is quite probable that no such bag exists; and if so, this would 

 make a wider distinction between Hemicalanus and Diaptomus. 



The particular character of the organs of the mouth and other 

 parts in the Hemicalani, will be gathered from the figures and the de- 

 scriptions beyond. 



There are some species that have all the Calanoid characteristics of 

 this genus, in which minute inferior eyes are distinguishable, as in 

 Pontella. It may be doubted, whether the existence of these eyes 

 should require us to place them with the Pontella, or whether we 

 should regard as more important the characters of the posterior 

 antennae, and arrange them with this genus. The former course has 

 been adopted. The character of the posterior antennae more espe- 

 cially referred to, is their having only three setae at the extremity of 

 the shorter or anterior branch, five being the typical number for Pbn- 

 tella. 



The species of this genus, here described, are all oceanic, occurring 

 in the pure ocean waters, like the Pontellae and unlike the Diaptomi. 



Hemicalanus longicornis. 



Frans rotundatus. Oephalothorax posticd obtusus, 5-articulatus, articulis 

 posticis cequis. Oculi codliti, minuti. Antennce anticce sesqui cor- 

 poris longitudine, rectiusculce, setis brevibus, duabus subapicalibus 

 posticis prcelongis, subcequis, apicalibus perbrevibus, anticd penultimd 

 artieuli longitudine. Styli caudales breves. 



Front rounded. Cephalothorax obtuse behind, five-jointed, four pos- 

 terior segments subequal. Eyes united, minute. Anterior antennas 

 one and a half times as long as body, nearly straight, the tips 

 nearly in line of beak; setae short, two posterior subapical quite 

 long, subequal, apical very short, anterior penult as long as penult 

 joint. Caudal stylets very short, the setae spreading, subequal, not 

 longer than abdomen. 



*©*' 



Plate 78, fig. 9, animal, enlarged. 



