Gammarus duhiiis tS' G. nolens. 179 



t)r. Leach, i must confess I can see no necessity or propriety 

 in generically separating animals similar in habits, and, so far a* 

 Ave know, in structure : and at all events the attempt seems pre- 

 mature, as our acquaintance with the species is as yet too limited 

 to enable us to appreciate the rank and value of the respective 

 characters. 



4. Gam. nolens. 



Desc. Bod}; about three or four lines long, not much com- 

 pressed, smooth, corneous, red after death. Antenncc not more 

 than one-third the length of the body, slender, tapered, with a 

 w horl of short spines at each articulation : superior shortest, three- 

 jointed, all the joints short : inferior four-jointed, basilar joint 

 shorter than the second or third. Eyes black, roundish, placed 

 at the base of the antenna, not marginal. Arms monodactyle ; 

 first pair with a small hand ; the second with the hand more 

 dilated, hairy on their inner margins. Legs monodactyle, spi- 

 nous ; spines not collected into fascicules, with the exception of 

 the little bunch of hairs at the foot of the claws, which seems com- 

 mon to the genus. Caudal processes two pairs, with the branches 

 mucroxiate. Tail short, smooth and simple above, terminating in 

 a papilla, but without terminal processes. 



Hub. Amongst conferva;, not rare. 



Obs. To the preceding species I gave the specific appellation 

 dubius, since it seemed doubtful to which of the genera of Dr. 

 Leach it ought to be referred ; this I have named nolens, as it 

 will arrange with none of them. It seems allied to the Gam- 

 marus monoculoidcs (Linn. Trans, xi. 5. tab. ii. fig. 3.) of Mr. 

 Montagu. 



I have carefully compared the species just described with those 

 of Montagu in the 7th, 9th, and 1 1 th volumes of the Linnean 

 Transactions ; and with those of Dr. Leach in the Edinburgh 

 Encyclopedia, in the Supplement to the Encyclopedia Dritan- 

 nica, and in the Entomologist's Useful Compendium of Mr. 

 Samouellc, and I entertain no doubt of their being perfectly dis- 

 tinct from any known to those eminent naturalists. "With the 

 exception of the G. maciilaiuSy of which I have seen a single 

 M 2 



