Gammarus duhiusSf 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 as 

 we 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.noleUS. 



Desc. Body about three or four lines long, not much com* 

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

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

 whorl 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 antennae, not marginal. Arms monodactyle ; 

 iirst 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 

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

 a papilla, but without terminal processes. 



Hab, Amongst confervae, not rare. 



Obs, To the preceding species I gave the specific appellation 

 dubiusy 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 monoculoides (Linn, Trans, xi. 5. tab. ii. fig. 3.) of Mr.. 

 JMontagu. 



I have carefully compared the species just described with those 

 of Montagu in the 7th, 9th, and 11th volumes of the Linnean 

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

 Encyclopaedia, in the Supplement to the Encyclopaedia Britan- 

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

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

 tinct from any known to those eminent naturalists. With the 

 exception of the G. maculahis, of which I have seen a single 



M 2 



