REPORT ON THE CRUSTACEA MACRURA. 



781 



face superieure est fortement arquee et comme bossue," which the following table 

 represents : — 



Palemoniens : 

 Ayantlesant. 

 int. terminees 

 par 



Trois filets 



multiarticules. 



Pattes de la deuxieme 

 paire filifornies et a 

 carpe multiarticule, 



Pattes de la deuxieme 

 poire plus fortes que les 

 anterieures, et n'ayant 

 pas le carpe devise 



Abdomen bossu en dessus, . 

 Abdomen non bossu en dessus, 



Lysmata. 



Leander. 

 Palxmon. 



Stimpson accepted the genus Leander of Desmarest, but established it upon totally 

 different characters from those of the author. 1 His words are : — " Genus Leander, 

 E. Desmarest. Carapax spina antennali et spina branchiostegiana armatus ; spina 

 hepatica nulla, species plerumque maricohe. Typus Palxmon natator M. Edwards." 



This will be seen to correspond w x ith the description of Pcdsemon, which has the 

 " spina branchiostegiana " and has no " spina hepatica," according to Leach's type 

 still preserved in the British Museum. 



Synoj)sis of the Genera included in the original Genus Palgemon of Fabricius. 



Palxmon, 



Palxmonella, 1852, . 



Bithynis, 1836, 



Rostrum deep, serrate above 

 and below. 



Rostrum slender, serrate 

 above and below. 



Rostrum deep, serrate above 

 and below. 



Having the frontal margin of the carapace armed with 

 two antennal teeth, one above the other. Second pair 

 of pereiopoda with carpos long. Type, Palxmon 

 serratus (Pennant) and Palxmon squilla (Linne). 



Having one tooth on the frontal margin, and a second on 

 the hepatic region in nearly the same horizontal line. 

 Second pair of pereiopoda with carpos not long. 

 Palxmonella tenuipes, Dana. 



Having one tooth on the frontal margin, and a second on 

 the hepatic region nearly in the same horizontal line. 

 Second pereiopod with the carpos long. Type, 

 Bithynis lar (Fabricius). 



\ One tooth on the frontal margin, and a second on the 

 Brachy carpus, n. gen., Rostrum deep, serrate above j hepatic region, below the horizontal line. Second 

 and below. pereiopod with the carpos short. Type, Brachycarpus 



savignyi (PI. CXXIX.) 



Palxmonella, Bithynis, and Brachycarjms can only be considered as varieties of 

 Palxmon, yet they are such decided forms that they may be easily distinguished. 



Geographical Distribution. — The species of this genus as defined in this Report 

 are among the best known of the European species, and form one of the most favourite 

 delicacies of the table. 



Most of the species recorded by Milne-Edwards are from the coasts of Europe, but 

 Palxmon quoianus is from New Zealand, Palxmon natator is found in the Indian 

 Ocean, and has since been found in the middle of the Atlantic upon floating weed. 



1 Loc. cit., p. 109. 



