M. T. Thorell on the Species of the Argulide. 443 
This extremely short and meagre description is accompanied 
by a coarse woodcut representing the animal from beneath, but 
in which we can distinguish neither antenne, “sting,” nor shape 
of the mouth-tube. There seem to be no comb-like teeth on the 
hinder foot-jaws. The tail is described in the following words :-— 
“Then [on the abdomen] follow two short folia, covered by two 
others, each of them nearly as long and as broad as the exposed 
part of the abdomen.” The species undoubtedly stands near 
A. funduli, but seems to be distinguished by a somewhat longer 
head-shield, a longer and more deeply cloven tail, with more 
pointed lobes and smaller sucking-cups. Whether the feet 
possess flagella (gissel) or not, is not to be learnt from either 
description or figures. 
This Argulus is, according to Gould, found on the “ Alewife,” 
which he identifies with the European Alosa vulgaris. Probably 
the fish in question was an Alosa tyranntus, Dekay, which, ac- 
cording to Valenciennes *, is the Alewife of the United States. 
In ‘Silliman’s Journal,’ (1839) vol. xxxvi. p. 393, under the 
title “ New Species of Argulus; notice from Dr. T. W. Harris,” 
we find the following remarks :—‘“ It may interest some of your 
readers to be informed of the discovery of another species of 
Argulus in this country. It was found in the gills of a herring 
caught upon Brighton Bridge, from Charles River, during the 
month of June last. It differs from Argulus foliaceus of Europe, 
and from the species described in a former number of your 
Journal, vol. xxxiv. p. 225+, in the size and form of the body and 
in the shortness of the legs. Having presented the specimen to 
Dr. A. A. Gould for description, I shall not attempt to anticipate 
him by giving a detailed account of its specific characters at this 
time.” 
It is undoubtedly A. alose which is here alluded to; for 
Gould says, with reference to this specimen, that it was presented 
to him by Dr. T. W. Harris, who found it on the branchiz of the 
“ Alewife,” which fish in America, like the Alosa vulgaris with us, 
is often confounded under the general name of “herring” or 
“sill.” Gould has described no other species of Argulus. That 
the species differs from A. foliaceus in the shortness of the legs, 
is a mistake. See the diagnosis. 
12. A. elongatus, Hell. 
Syn. Argulus elongatus, Heller, Sitzungsber. d. Kais. Akad. d. Wissensch., 
Math.-Naturwissensch. Cl., (1857) xxv. p. 106, taf. 3. figg. 1-4. 
Scutum cephalicum minimum, longitudine trunci, inverse sub- 
* Cuvier et Valenciennes, ‘Histoire Naturelle des Poissons,’ (1847) 
tom. xx. p. 421. 
+ This probably means vol. xxxi. p. 297, where A. catostomi, Dana, is 
