REPORT ON THE CRUSTACEA MACRURA. 577 



First pereiopod chelate ; carpos not, or but slightly, excavate. 



Second pereiopod chelate ; carpos seven-articulate. 



Branchiae six in number ; niastigobranchiae five, rudimentary. 



Nauticaris, n. gen. 



Carapace without supraorbital, but with an antennal tooth. Rostrum com- 

 pressed, slender, serrate. 

 Mandible with triarticulate synaphipod ; without psalistoma. 

 First pereiopod chelate ; carpos not excavate. 

 Second pereiopod chelate ; carpos seven-articulate. 

 Branchiae thirteen in number; mastigobranchiae six, rudimentary. 



Hetairus, n. gen. 



Carapace with one supraorbital and one antennal tooth. Rostrum long, narrow, 



and dentate. 

 Mandible with two-jointed synaphipod ; without a psalistoma. 

 First pereiopod chelate ; carpos not excavate. 

 Second pereiopod chelate ; carpos seven-articulate. 

 Branchiae six in number ; mastigobranchias four, rudimentary. 



Merhippolyte, n. gen. 



Carapace without any supraorbital teeth. Rostrum long, slender, serrate. 



Mandible with triarticulate synaphipod, and with psalistoma. 



First pereipod chelate ; carpos not excavate. 



Second pereiopod chelate ; carpos multiarticulate. 



Branchiae twelve in number ; mastigobranchiae six, rudimentary. 



Chorismus, n. gen. 



Carapace without any supraorbital tooth. Rostrum long, deep at base, laterally 



compressed. 

 Mandible with triarticulate synaphipod, and rudimentary psalistoma. 

 First pereiopod chelate ; carpos not excavate. 

 Second pereiopod chelate ; carpos multiarticulate. 

 Branchiae seven in number ; mastigobranchiae four. 



(ZOOL. CHALL. EXP. — PART LII. — 1887.) Fff 73 



