394 
GAMMARIM. 
Gervais, who first clearly pointed out the distinction 
between it and De Geer’s smooth-tailed species, for 
which he retained the name of G. pulex. As already 
stated, we fear that M. Milne Edwards has fallen 
into some confusion in treating upon these fresh-water 
species. He placed one, to which he applied the name 
of G. fluviatilis, in his section without teeth on the 
anterior, but with small spines on the posterior segments 
of the tail ; hut he refers his species not only to De Geer, 
whose figures perfectly agree with this sectional charac- 
ter, hut also to Rosel, Geoffroy (whose pi. xxi. fig. 6, 
is copied from Rosel), and to Gervais, all of whom as 
certainly intend a tooth-hacked species. To add to the 
confusion, M. Milne Edwards expressly says that the 
penultimate joint of the peduncle of the superior an- 
tennas reaches the tip of the peduncle of the lower ones ; 
and adds, under G. marinus , that the sixth pair of caudal 
appendages scarcely extend beyond the extremity of the 
preceding pair of the same organs. The other fresh- 
water species of M. Milne Edwards is still more un- 
intelligible ; this he names G. pulex, placing it in the 
section which has no teeth on the first three segments, 
and no spines on the posterior segments of the tail, and 
giving as its references, Geoffroy, Linnaeus (?), Fabricius, 
and Latreille, all doubtful, as well as Montagu, Desma- 
rest, Zenker, and Gervais, whose species has spines on 
the terminal segments of the tail. 
We have stated above that Linnaeus employed the 
name Pulex aquaticus in the Fauna Suecica exclusively for 
a marine or littoral species, but in his Systema Nature 
he says : “ Habitat ad maris littora, etiam in fontibus et 
fossis,” thus confounding a sea and a fresh-water species 
together ; but we have not the slightest means of knowing 
to what fresh-water species he alluded. Fabricius, on 
the other hand, although he quotes De Geer’s figures 
