DECAPOD A. PAL.EMONJDJE. 



MACRUURA, 



GENUS HIPPOLYTE. 



CANCER. 0. Fabr. 



PAL/EMON. Olivier. 



ALPHEUS. Lamarck, Risso, Sabine. 



HIPPOLYTE. Leach, Desmar., Roux, Edw. 



Generic Character. External antenna placed beneath the 

 internal ; the scale externally unidentate. Internal antenna 

 terminating in two filaments : the superior thick, strongly ciliated, 

 and excavated beneath ; the inferior slender and setaceous. Ex- 

 ternal pedipalps slender and pediform. First pair of feet short, 

 equal, didactyle : second pair long, unequal, minutely didactyle ; 

 the wrist many-jointed : remaining pairs simple. Carapace fur- 

 nished with a deep rostrum, the carina of which extends over 

 a considerable portion of the median line of the carapace. Abdo- 

 men abruptly bent downwards at the third segment, which is 

 gibbous, and produced posteriorly. 



OF this genus, which was first established by Leach, 

 there are several species inhabiting our coast. They 

 may be at once distinguished from all other Paleemonidte 

 by the peculiar character of one filament of the internal 

 antennae, which is broad and excavated in its inferior sur- 

 face. The rostrum is very deep in most species, and the 

 wrist multi-articulate in all. The abrupt curvature of the 

 abdomen varies considerably in the different species. 



