M Y S I D E A. 



651 



totis palpo natatorio extus instructis. Pedes abdominis natatorii, sub- 

 cequi. [Segmentum abdominis in specie scrutatd posticurn emarginatum 

 vel bilobatum7[ 



Near Mysis. First antennae having two flagella and an oblong scale 

 at apex of base. Eyes symmetrical, short. Thoracic feet twelve, 

 tarsus not jointed, unguiculate; four pediform maxillipeds; second 

 pair of maxillipeds and all the feet with a natatory palpus. Abdo- 

 minal feet natatory, subequal. [Last segment of abdomen in the 

 known species emarginate or bilobate behind.] 



This genus is closely allied to Mysis, from which it differs in not 

 having the tarsus many-jointed. The abdominal feet are all well deve- 

 loped and natatory. The first antennae have an oblong lamella at 

 apex of basal portion, as well as two long multiarticulate flagella; one 

 of the flagella (the upper) commonly is slightly stouter at base, and 

 hairy in this part on one side. 



Seven pairs of pediform organs have similar natatory palpi : but 

 the first of these pairs is shorter than the following, and is thrown 

 forward with the extremity downward, while the others are flexed 

 outward and forward ; it is, therefore, properly a pair of maxillipeds. 

 Anterior to these organs, there is another pair of maxillipeds slightly 

 stouter than the second pair, and having a similar position. 



The inner caudal lamellae have a small, transparent, globular gland 

 in the basal portion, like Mysis. 



Promysis orientalts. 



Carapax breviter restrains, rostro oculis multo breviore. Antennas in- 

 ternal apice basis valde crassw, artieulo tertio vix oblongo. Pedes 

 thoracis gracillimi, breviter et sparsim eiliati, ungue oblongo, tenuissimo, 

 palpo multo breviore quam ramus pediformis. tegmentum abdominis 

 posticurn supra longitudinal iter concavum, lamellis caudalibus valde 

 brevius, basi latius et crassius, apice paulo furcatum et acutwn, mar- 

 ginibus breviter spinulosis. Lamella caudalis externa interna multo 

 longior, extus intusque ciliata. 



Carapax short beaked, beak much shorter than the eyes. Interior an- 



