JOURNAL 



OF THE 



Academj of Natural Sciences 



or 



PHILADELPHIA. 



No. 4. AUGUST, 1817. Yoi. I. 



On a New Genus of the Crustacea^ and the Species 07i 

 which it is established. By Thomas Say. Read 

 July, 8, 1817. 



Order MACROURI. 



Genus CERAPUS^ 



Essential Character, — Thumb of the second pair, of 

 feet biarticulate; Interior antennae four jointed, exterior 

 ones five jointed. 



Artificial Character, — Antennas subequal, interior 

 ones 4-jointed, exterior one 5-jointed. Two anterior 

 pairs of feet monodactyle, the second pair with a two 

 jointed thumb. 



Natural Character, — Body seinicylindrical, somewliat 

 linear, decreasing towards the tail, ten-jointed. Head 

 distinct from the first joint and larger, quadrate, a little 

 elongated into an angle near the base of the interior anten- 

 nae, each side, for the reception of the eyes, which are 

 hardly prominent. Antennae nearly equal, very large, 

 interior ones with the first joint thicker, second and third 



* From Jtf /)«f, a horn, and Troy?, a foot, in allusion to the animal em- 

 ployinti its aniennae as feet. 



Vol. L D 



