6. Body flattened sideways; some of the body appendages much different 



from the others; often jumping animals 

 Amphipoda Amphipods or Scuds 

 Body flattened dorso-ventrally; legs (except first and last) practically 

 alike; rarely jumping 



Isopoda Isopods, Sowbugs or Pillbugs 



7. Carapace joined to three or less thoracic segments; all of the thoracic 



appendages two-branched; eggs carried in an egg sac at the base of 

 the peraeopods of the female 



Mysidacea, Mysis rehcta Loven Opossum Shrimp 

 Carapace joined to all of the thoracic segments; most or all of the thoracic 

 appendages single (do not consider opposing claws on ends as 

 branches) ; eggs attached to the pleopods 



Decapods Crayfishes, Shrimps and Prawns 



KEY TO THE PRINCIPAL GENERA OF PHYLLOPODS 

 OR FAIRY SHRIMPS 



1. With a shell or carapace 2. 

 No shell or carapace — Anostraca 9. 



2. Shell in one piece; flattened dorso-ventrally, and covering only the an- 



terior part of the body — T^otostraca 3. 



Shell bivalve, flattened laterally, and enclosing the animal — Conchostraca 



4. 



3. With only two slender processes projecting from the end of the abdomen 



Apus Schaeffer (of Family Apodidae) 

 With a central paddle-shaped appendage between the two slender prO' 

 cesses projecting from the end of the abdomen 

 Lepidurus Leach (of Family Apodidae) 



4. No concentric growth lines on the shell; Family Lynceidae 



Lynceus Miiller 

 (Limnetis Loven) 

 With concentric growth lines on the shell 5. 



5. With less than six concentric growth lines on the shell 



Enhynnadm Packard (of Family Limnadiidae) 

 With more than fifteen concentric growth lines on the shell 6. 



6. With a frontal appendage on the head; shell covering head; Atlantic 



states 



Limnadia Brongniart (of Family Limnadiidae) 

 No frontal appendage (process between the antennae) 7. 



7. With a spine on the rostrum (Family Leptestheriidae) 



Leptestheria Sars 

 (Estheria Riippcll (part) ) 

 No spine on the rostrum; Family Caenestheriidae 8. 



8. With fourteen or fifteen segments in the flagellum of the second antenna 



Caenestheriella Daday 

 (Estheria Riippell (part) ) 



178 



