332 REPORT OF NEW JERSEY STATE MUSEUM. 

 Super-Family ASTACIDEA. 



The Craiviishes. 



Thoracic sternum Avith all segments usually, though not in- 

 variably, firmly united and abdominal terga overlap one another. 

 Longitudinal sutures of carapace absent, though cervical fre- 

 quently present. Carapace united in front to epistome. An- 

 tennal scale small or obsolete. 



Families rather few, and only one represented in our region. 



Family ASTACID.^. 

 The Craiviishes. 



Carapace subcylindrical, with distinct rostrum developed an- 

 teriorly. Carapace posteriorly produced over anterior half of 

 first somite, though not kept down by pleocleis. Segments of 

 pleon dorsally imbricated or overlapping each other. Second 

 antennae with long multiarticulate flagellum,. Peraeopods seven- 

 jointed, first three pairs chelate, and first pair longest. Rhipi- 

 dura well developed, and outer ramus with a diaeresis. Mas- 

 tigobranchiae, or epipodal plates, large, with well developed 

 podobranchial plume attached to all trunk-legs except last pair. 

 Outer branch of uropods with transverse suture. 



Six genera are included in this family by Stebbing, though 

 only one represented on our shores, and one fresh water. 



Snh-Faniily Astacin.^. 



Hands of chelipeds large, broad, edges round, surface con- 

 vex. 



Key to the genera. 



a. Last thoracic segment not mobile ; species marine. homarus 



aa. Last thoracic segment free from rest ; species fresh water. cambarus 



