GAMMARUS DUBIUS. 
397 
A MP HI POD A . GA MM A RIDES. 
NATATORIA. 
DOUBTFUL SPECIES. 
We are under the necessity of introducing in the present situation two species 
described as belonging to the present genus, by our late friend Dr. G. 
Johnston, of Berwick-upon-Tweed, of which we have unfortunately been un- 
able to meet with any specimen, either in the British Museum collection 
or amongst the species which he forwarded to us some years since, for 
the purposes of the present work. We therefore transcribe his descriptions 
of them. 
GAMMARUS DUBIUS. 
Johnston, Zool. Journ. iii. p. 178. 
“ Body between two and three lines long, smooth, 
corneous ; when dead becoming yellowish-brown ; marked 
across the hack with a few red lines. Antennse rather 
more than one-half the length of the body, slender, 
nearly equal, armed with very short weak spines ; basilar 
joint of the superior longer than the second or third, 
which indeed might, with as great propriety, he reckoned 
amongst the articulations of the last joint [flagellum] 
as distinct joints ; basilar joint of the inferior shorter 
than the succeeding. Eyes black, roundish, placed at 
the base of the antennae. Arms with nearly equal 
hands, monodactyle, oblong, and not much dilated, and 
sparingly ciliated. They very much resemble those of 
G. punctatus* in their form, but are rather smaller in pro- 
portion to the body. Legs spiny, spines not collected 
into fascicles, but distributed along the whole member ; 
and both the short anterior and long posterior legs are 
Amphithoe littomlis. Spence Bate. 
