Classification of the Decapod Crustaceans. 483 



nearly its own width. Ischiopodite very 

 broad. [Body somewhat oblong. Fir.st 

 antennoe not retractile into sockets. 

 Parasitic on corals.] Hapalocarcinidae. 



Ket/ to the Subfamilies of the Portuiiidae. 



I. Eye-stalk and orbits normal, 



A. Basal joint of second antenn?e narrow, 



[Flagella of second antennae not shut out 

 from orbits.] 

 i. First antennae sloping. Front with a 



median tooth. Geueralh' at least one 



pair of walking-legs as long as chelipeds. 



1, Last pair of legs not distinctly natatorial. Carcinidince. 



2. Last pair of legs distinctly natatorial . Purtummnce. 

 ii. First antennae transverse. Front with a 



median notch. Chelipeds longer than 

 walking-legs. 



1. Last joint of fifth legs lanceolate .... Catoptrince. 



2. Last joint of fifth legs rounded CarupiiKe. 



B. Ba-'al joint of second antennae broad, 



[Chelipeds longer than walking-legs.] 



i. Flagella of second antennae not shut out 

 from orbits by processes of the basal 

 joints Portunino'. 



ii, Flagella of second antennae shutout from 

 the orbit by processes of the basal joints. 



1. Last joint of fifth legs sickle-shaped . , Caphyrince. 



2. Last joint of fifth legs flattened Thalamitina . 



II. Eye-stalks enormously long, orbits extend 



across the whole fore edge of the carapace. 

 [Chelipeds longer than legs. Antennae free ; 

 basal joint short ; flagella not shut out from 

 orbits.] PodophthalmiiKB. 



Key to the Subfamilies of the Potamonidse. 



I. Outward channels from gill-chamber covered 



by first maxillipeds, reaching to front. 



[Third maxillipeds with meropodites not 



longer than broad, subtriangular, bearing 



carpopodites at apex, with good exopodites.] Deckenmia. 

 11. Outward channels from gill-chamber not as 



in Deckeniiuae. 



1. Endostome ridges project on fore edge of 



mouth, Exopodites of third maxillipeds 

 more or less reduced. [Meropodites of 

 same subtriangular, not longer than broad, 

 with carpopodites at apex.] Potamocarcirwice. 



2. Endostome ridges do not project on fore edge 



of mouth. Exopodites of third maxilli- 

 peds not reduced, 

 i . Meropodites of third maxillipeds not longer 

 than broad, subquadrate, with carpo- 

 podites at inner angles Potamoninu: 



