ORDER DECAPODA — PALEMON. 29 



GENUS PALEMON. Fabricius. 



General form of the preceding. The internal antenna arise above the external ones, and ter- 

 minate in three filaments. The first two pair of feet didactyle ; the second longer and 

 more robust than the first ; the remaining feet monodactyle. 



Palemon vulgaris. 



PLATE IX. FIG. 30. 



Palemon vulgaris. Say, Jour. Acad. Nat. Sciences, Vol. 1, p. 248. 



P. id. Milne-Edwards, Hist. Nat. des Crustac^s, Vol. 2, p. 396. 



P. squilla ? Gould, tnvertebrata of Massacliusetts, p. 332. 



Description. Rostrum acute, cultrate, dilated, and deepest under the middle, extending 

 somewhat beyond the lamellar appendices of the external antennas, with eight or nine teeth 

 on the upper edge, and three or four beneath with setae between them. Shield with two minute 

 spines on the antero-lateral border at the bases of the external and internal antennaj ; between 

 the two spines, an obsolete furrow directed backwards. Peduncle of the lamellar appendix 

 with a spine at the exterior tip. Two spines on the first joint of the interior antenna;. The 

 fingers of the first pair scarcely reaching middle of the palm of the second ; its carpus with 

 a spine, and longer than that of Ihe second ; its fingers hirsute, minute, and nearly equalling 

 the palm. The second pair with its fingers shorter than the palm ; carpus shorter than the fol- 

 lowing joint ; hands elongate ; finger somewhat deflexed ; thumb straight. Medial caudal 

 plate with two movable prostrate spines placed on each side ; tip with three or four movable 

 spines. External antennje two inches long. 



Color, light transparent sea-green mottled with brown ; ocular peduncles spotted with 

 yellow. 



Total length from the extremity of the rostrum, 1 "5. 



This species is closely allied to the P. serratus, or Prawn of England, which is there con- 

 sidered as a great delicacy. Our species is usually termed Shrimp, or Big Shrimp, to dis- 

 tinguish it from the C. septemspinosus before described. It is distinguished from the English 

 Prawn by the rostrum, which in this latter is bifid at the tip, and greatly exceeds the lamel- 

 lar appendix of the external antennse ; it is also smooth near the front above, and the animal 

 is from three to five inches in length. It is closely allied to P. squilla of Europe {La Cre- 

 vette of the French), which is somewhat larger, with the rostrum straight, and not exceeding 

 the lamellar appendix of the external antenna;. The relative lengths of the fingers of the 

 second pair in the two species disagree ; but without a direct comparison of specimens, it is 

 impossible to determine in what particulars they may differ. 



