158 M. T. Thorell on two European Argulide. 
in the integument of the animal upon which the parasite has 
fixed itself, and that the imbibed blood-corpuscles, on their way 
through the narrow gullet, are broken and ground by the 
mandibles. 
In those forms (for instance the species of the genus Gyro- 
peltis) which lack maxille, the mandibles are placed close to 
the opening of the mouth, and may, being strongly toothed on 
the lower border, unite the functions which we observe to be- 
long to the mandibles and maxillee in A. foliaceus and the allied 
species. 
Within both mandibles and maxille other perfectly similar 
mandibles or maxille are usually perceptible, differing from these 
only in being somewhat smaller. These are probably formed to 
replace the older external organs when a change of the integu- 
ment takes place: a similar supplemental structure is found 
in the claw of the antenne of the first pair. In A. coregoni the 
oral organs exhibit almost the same formation as in A. foliaceus. 
A. purpureus differs especially in having the mandibles situated 
lower down, close to the opening of the mouth, and in the 
maxille being destitute of teeth on their inner border. The 
lip also has a different form. 
After these remarks on the morphology of the Argulide we 
pass on to the description of our two species, A. purpureus and 
A. coregoni. 
IE 
Argulus purpureus, Risso *. 
Syn. meee bicornutus, Risso, Hist. Nat. d. Crustacés de. Nice, (1816) 
is ae Risso, Hist. Nat. d. princip. prod. de Europe 
mérid. tom. v. (1826) p. 139, pl. v. fig. 28. 
Scutum cephalicum maximum, oblongum, multo longius quam 
latius, in lateribus parum rotundatum, antice utrinque pro- 
funde sinuatum, postice anguste et profunde incisum, pedes 
omnes totamque caudam tegens; segmentum trunci ultimum 
utrinque lamina foliacea preeditum ; cauda ampla, latissima, 
dimidiam reliqui corporis longitudinem zequans, vix ad medium 
incisa, lacmiis acuminato-rotundatis; stimulus longissimus ; 
sipho subcylindratus ; cotyledones parvi, diametro {1, longit. 
corporis zquantes ; pecten plaga media scabra nulla, dentibus 
tribus acutis ; pedes flagello carent.—Longit. circa 18, lat. 
10 millim. (2). 
Hab.in Mari Mediterraneo ad Niczeam, in Selenia (Carang?) luna (Geoftr.) 
* Although the name bicornutus is older than purpureus, we prefer the 
latter, on the ground that the former appellation is based on a false appre- 
ciation of the antenne; we have less hesitation in doing this, since no 
personal right of priority is thereby affected. 
