STALK-EYED CRUSTACEA 481 



I. Palaemon. 



PalcEinon Fabricius, Leach, Spence 



Bate. 



Palemon H. Milne Edwards. 



Leander Desmarest, Stimpson. 



Carapace less than a third the length of the animal 

 posteriorly smooth, slightly compressed anteriorly, elevated 

 into a crest over the frontal region, and produced to a 

 long rostrum that is armed above and below with teeth. 

 The orbital notch is well defined, but has no tooth. At 

 the outer canthus a strong first antennal tooth projects 

 below it, and still farther down a second tooth stands 

 within the margin on a level with the external antennje, 

 and above the line of the fronto-lateral angle. There 

 is no tooth on the hepatic region, but a depression or 

 fissure. The abdomen is smooth, dorsally rounded ; 

 the appendages are robust and two - branched ; the 

 telson tapers to a central tooth, and has dorso-lateral 

 spines ; the lateral wing of the swimming organ has a 

 division. 



The eyes are short, broad, unarticulate, and supported 

 on a slender pedicle ; the cornea is hemispherical, and 

 has an ocellus that is sometimes distinct. The internal 

 antennae have the first joint compressed above and below, 

 and armed on the outer margin with a sharp spine, and 

 at the anterior distal angle with a flattened tooth ; the 

 second joint is thicker than the first, shorter on the upper 

 surface than on the lower, and articulates obliquely with 

 the third joint, that supports two long flagella, of which 

 the upper and outer sends off a third that is shorter than 

 the others. The external antennae are armed with a 

 tooth at the outer and lower distal angle of the first joint 

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