4.40 M. T. Thorell on the Species of the Argulide. 
of Milne-Edwards and Baird above cited. It is not impossible 
that, under the appellation A. foliaceus, two separate species 
have been confounded. The figures which Vogt * has given of 
this animal differ from the Swedish (and consequently from the 
genuine) form in having the tail much smaller and almost bent 
inwards laterally. Jurine and Baird represent the tail such as 
I haye found it in my own specimens. 
4. A. coregoni, Thor. 
See page 162. 
5. A. pugettensis, Dana. 
Syn. Argulus pugettensis, Dana, United States’ Explormg Expedition, 
Crustacea, (1853) il. p. 1351, pl. 94. fige. 2 a et d. 
Scutum cephalicum oblongum, ellipticum, pedes omnes tegens ; 
cauda magna, oblonga, longitudine circa 2 reliqui corporis, 
et latitudine 2 latit. scuti fere eequans, usque ad medium in- 
cisa, laciniis subacuminatis; stimulus Be sipho sub- 
clavatus; cotyledones sat magni, diametro 1-1 corporis lon- 
gitudinis eequantes ; pectinis “dentes 3 3 subconici; dentes 2 
inter maxillipedes secundi paris adsunt.—Long. circa 17, 
latit. 10 millim. (9 ?). 
Hab. in America boreali (ad oras occid.: “ Puget’s Sound”). Hospitium 
ignotum. 
This very scanty description contains nothing respecting the 
oral organs; but the accompanying figures, which seem to be 
good, and which present the animal both from the dorsal and 
ventral aspects, show so strong a likeness to the two species im- 
mediately preceding, that I have not hesitated to place it in the 
same subdivision of the genus with them. The tail is propor- 
tionally larger, and especially broader at the base, than in A, 
coregont. 
6. A. catostomi, Dana et Herr. 
Syn. Argulus catostomi, Dana et Herrick, Silliman’s Amer. Journ. (1837) 
xxxi. p. 297. figg. 1-11; Milne-Edwards, Hist. Nat. d. Crustacés, 
il. p. 445. 
Scutum cephalicum amplum, suborbiculatum, paullo latius quam 
longius, antice utringue subsinuatum, pedes quoque ultimi 
paris ad partem tegens ; cauda lata, rotundata, longitudine 
circa } reliqui corporis, postice non usque ad medium i incisa, 
laciniis late rotundatis ; ; stimulus longus; sipho ovatus ; coty- 
ledones mediocres; pecten plaga media scabra subtriangula, 
dentibusque 3 late truncatis ; inter maxillipedes secundi paris 
dentes null, Ramus inferior pedum primi paris articulis 3, 
* Loc. cit. 
