472 Mr. L. A. Borradaile oji the 



wanting on some or all legs. Freshwater 



forms Atyidae. 



II. CheliB not as in Atvidoe. Exopodites on all 

 legs. Deep-sea forms. 



1. Last three pairs of legs abnormally long. 



A lash on the exopodite of the first 



maxillipeds Nematocarcinidae. 



2. Last three pairs of legs not abnormally 



long. No lash on the exopodite of the 



first maxillipeds Hoplophoridae. 



Kei/ to the Sulifamilies of the Pandalidfe. 



I. Second wrists undivided Thalassocarina;. 



II. Second wrists subdivided Pa?idalince. 



Key to the Families of the Palgemonoida. 



I. Second wrists subdivided. 



1. First legs much stronger than rest. Eyes 



usually covered by carapace. [Mastigo- 

 branchs of legs and mandibular palps 

 present.] Alpheidae. 



2. First legs not much stronger than rest. 



Eyes not covered by carapace. [Mastigo- 



branchs of legs and mandibular palps J 



present or absent.] Hippolytidae. 



II. Second wrists undivided. 



1. Rostrum movable. Mastigobranchs on 



legs. [Mandibular palp present.] .:.... Rh3mchocinetid3e. 



2. Rostrum not movable. No mastigobranchs 



on legs Palaemonidse. 



Key to the Suhfamih'es of the Pala?monida3. 



I. First antennfe with two flagella (one usually 

 cleft for some distance from the tip). Third 

 maxillipeds have third joint fiat and often 

 broad. 



1. Mandibles with palps. Propodites of 



second legs, third maxillipeds, and one 



branch in first antennae broad and flat . . Hijmenoceriiup. 



2. Mandibles without palps. Limbs not 



broadened as in Ilymenoceriiife PontonlincB. 



II. First antennas with three flagella (owing to 

 cleavage of one almost or quite to the base). 

 Third maxillipeds pediform. [Mandibular 

 palps usually present.] rakemonincc. 



Key to the Families of the Crangonoida, 



I. One or both legs of first pair chelate. 



Rostrum short, compressed. 

 [1. Second legs simple Autonomaeidae.] * 



* The only ground for placing here the very obscure genus Auto- 

 tiotno'a is that Risso, who described it, thought it related to Processa. 



