162 M. T. Thorell on two European Argulide. 
Selenia luna (Geoffr.), Bonap. (le Caranx magnifique, Citula 
Banksii, Risso), commonly attached to the base of the pectoral 
of that fish. The female was unknown to him: the male is 
distinguished by “ deux petits tubercules coniques, blanchatres 
.... situés A la base de la derniére paire de pattes.” In colour 
it is said to be ‘‘ d’un pourpre violdtre, traversé par six lignes 
longitudinales paralléles, blanchatres.” The description in ‘ Hist. 
Nat. d. Crustacés de Nice’ is extremely detailed, but contains 
many inaccuracies. The description in ‘ Hist. Nat. d. prince. 
prod. de l’Kurope mérid.’ would seem to be only an abstract of 
the former. It is accompanied by a figure, in which it is not 
easy to recognize an Argulid. In his first-mentioned work, 
Risso gives correctly the affinities of the animal, and places it in 
Geoffroy’s genus Binoculus, under the name of B. bicornutus. 
But in the later work we search in vain for either Binoculus or 
Argulus ; with his usual superficiality, Risso there removes the 
animal to the family Bopyride, under the name of Agenor (n. g.) 
purpureus, by the side of species of the genera Bopyrus and Ce- 
crops! A. purpureus deserves, more than any other species of 
Argulus, to be made the type of a distinct genus (Agenor, Risso). 
Besides the unusual development of the head-shield, it is espe- 
cially characterized by the absence of the “ tassel” or flagellum 
(“ gissel”?) on the anterior pairs of legs, as also by the two 
lamellee on the last segment of the trunk. The parts of the 
mouth also show a somewhat different structure, as does the 
second pair of maxillipeds, in the peculiar ‘ patella” which is 
inserted between the second and third joints of these limbs. 
Argulus coregoni, n. sp. 
Scutum cephalicum antice utrinque subsinuatum, in 9? inverse 
subovatum, vix longius quam Jatius, pedes ultimi paris non 
tegens, in ¢ amplissimum, suborbiculatum, laciniis apice se 
invicem et omnes pedes tegentibus ; cauda ovata, longitudine 
3 reliqui corporis superans, saltem ad medium incisa, laciniis 
apice lanceolato-acuminatis; art. 18 antenn. secundi paris dente 
minuto armatus; stimulus minutus; sipho subcylindratus ; 
cotyledones sat parve, diametro 4—} longitudinis corporis 
eequantes ; pecten plaga media oblongo-rotundata scabra, 
dentibusque 3 conicis, acuminatis—Long. 9? usque ad 13, 
latit. ad 84 millim.; ¢ longit. 104, latit. 8 millim. 
Hab. in lacubus majoribus Sueciz mediz et septentrionalis ; in Storsj6n 
aliisque lacubus Jemtlandiz a Dr. C. L. Nystrém in Coregono lavareto 
Linn. et Thymallo vulgari Nilss. inventus; in LaxsjOn Dalslandiz in 
Coregono lavareto et in lacu Vettern in Satmone trutta Linn. a Dr. H. 
Widegren quoque captus. In cute externa piscium parasitat. 
Descr. Feminx. Corpus in universum eadem est forma atque in 
A. foliaceo: ovatum, depressum, supra modice convexum, Scutum 
