No. 26.] 



ARTHROSTRACA OF CONNECTICUT. 



FIG. I. Orchestia agilis. 



the body in length; or they may be short as in Orchomenella. 

 The first antennae only may be extremely short, as in Orchestia 

 and the females of the Hyperiidea. The second antennae are 

 usually more constant in their size but they too suffer considerable 

 reduction in female Hyperiidea and may be very large as in 

 Corophium and Siphoncecetes. 



The first antennae are made up of a peduncle of three segments, 

 followed by a flagellum usually multiarticulate, and sometimes 

 also by a secondary or accessory flagellum. The first joint of the 

 peduncle is characteristically very stout in the Lysianas sides. 

 The flagellum may be very short as in Orchestia. The accessory 

 flagellum is lacking in the Ampeliscidae, Orchestiidae, Stenothoe, 

 Sympleustes, Calliopius, Pontogeneia, Dexamine,iBatea, Amphi- 

 thoe, Ericthonius, Corophium, Siphoncecetes, and Podoceropsis. 

 In some few genera like Grubia and Jassa, it is quite rudimen- 

 tary and may easily be overlooked. Particular attention is 



