Key to the genera of the family PLATYSCELIDAE

1. Gnathopods 1 & 2 without carpal process; dactylus closing against concave distal margin of propodus. Pereopod 6; basis without fissure........................................................................ Tetrathyrus Claus, 1879

- Gnathopods 1 & 2 usually with carpal process, sometimes absent on G1, and very reduced on G2; propodus and dactylus normal. Pereopod 6; basis with fissure (sometimes small)........................................................ 2

2. Gnathopod 1 simple. Gnathopod 2 with small, or almost obsolete, carpal process................. Paratyphis Claus, 1879

- Gnathopods 1 & 2 chelate. Gnathopod 2 with carpal process longer than half of propodus............................ 3

3. Gnathopod 1; length of carpal process about half of propodus. Gnathopod 2; carpal process relatively slender, length about 0. 7 x propodus. Gnathopods 1 & 2; carpal process, and posterior margin of propodus, with very fine serrations. Antennae 2 of male with two distal articles longer than half preceding one...................................... Hemityphis Claus, 1879

- Gnathopod 1; carpal process usually longer than half of propodus. Gnathopod 2; carpal process as long, or almost as long, as propodus. Gnathopods 1 & 2; carpal process, and posterior margin of propodus, with distinct serrations. Antennae 2 of male with two distal articles shorter than half preceding one...................................... Platyscelus Bate, 1862