136 
Hos inger Isopoder fremtneder Parasitismen stserkere 
udprseget end hos disse eiendommelige Former, hvilket liar 
tilfplge en regressiv Udvilding af Hunnerne, ofte ledsaget 
af en paafaldende Assymetri. Hanneme er ligesom hos de 
mgte parasitiske Copepoder mcget ulig Hunnerne, saerdeles 
smaa og lever fastklamrede til disse. Alle hidtil bekjendte 
Former er Parasiter paa eller i forskjellige Crustaceer. 
Som eiendommelige Typer, <ler vel maa ansees som reprte- 
sentorcnde ligesaamange distinete Familier, kan nsevnes 
Slaigterne Bopyrus, Dajus, Entoniscus og Gryptoniscus. 
Fam. Dajidse. 
^en. N otophryxus, n. gen. 
Slsegtseharacteristik. Huiniens Legeme symetriskt, 
noget nedtrykt, lain tydeligt segmenteret i Midten af Ryg- 
siden; Sidedelene udvidede og opsvulmede. Hovedet mere 
eller mindre fremspringende, ikke tydeligt hegrsendset bag- 
til. Bagkroppen uleddet, pladeformig, nedentil concav. Fo- 
lerne rudimentsere, utydeligt leddede; 2 dot. Par coniskt til- 
spidsede i Fnden. Fodderne sammenti’Eengte paa et meget 
lidet Rum belt fortil, til hver Side af Mundregionen, kun 
tilstede i h Par. alle af ens Udseende og forestillende ufuld- 
stamdigt leddede Klamreorganer. Ingen tydeligt udviklede 
iEggeplader. Bagkroppen uden Lemmer eller andre Ved- 
hseng. 
Hannen af et lignende Udseende som hos Slmgteii 
Phryxus, med tydeligt segmenteret Legeme, 7 Par Klamre- 
fodder og uleddet Bagkrop. 
Parasiter paa lavere Podophthalmer (Schizopoder). 
Bemeerkninger. Ved Hunnens fuldkommen symetriske 
Legeme og Mangelen af de 2 Par bagerste Forkropsleminer 
stemmer denne Slasgt overens med Kroyers Skegt Dajus 
(Leptophryxus Buchholz), men skiller sig blandt andet meget 
vajsentligt ved Bagkroppens forskjellige Bygning og ved Man- 
gelen af egentlige fEggeplader. Arterne lever ligesom Dajus 
mysidis parasitisk paa lavere Podophthalmer (Schizopoder); 
men medens hin Form altid findes indsluttot i Kkekkehulen 
hos Mvsider, er de herhen horende Arter fastede frit til 
Rygsiden af deres Vserter (heraf Skegtsbeiuevuelsen). 
Foruden den nedenfor nsermere beskrevne Form, har j 
eg endnu ved vore Xyster fundet 2 andre distinete Arter, | 
In none ot the Isopods is parasitism more decidedly 
prominent than in these peculiar forms, which occasions a 
regressive development of the females, frequently accompanied 
by a striking assymetrv. The males are, as in the true 
parasitic Copepods, very unlike the females, exceedingly small, 
and pass their life firmly attached to the latter. All hitherto 
known forms exist as parasites, either on or in different 
Crustaceans. As characteristic types, that in all probabil- 
ity must be regarded as representing as many distinct fam- 
ilies, can be mentioned the genera Bopyrus. Dajus, Ento- 
niscus, and Gryptoniscus. 
Fam. Dajidse. 
Gen. TV otop]ir\yxii!S, n. gen. 
Generic Character. — • Body of female symmetrical, 
somewhat depressed, distinctly segmented in the middle 
of the dorsal side only; lateral parts dilated and tumes- 
cent. Head more or less projecting, not distinctly defined 
posteriorly. Abdomen non-atticulate, lamelliform, concave 
below. Antennae rudimentary, indistinctly articulate; 2nd 
pair conically pointed at extremity. Legs, of which occur 
but 5 pairs, crowded together over a very confined space, 
on either side of the buccal region, all uniform in appear- 
ance and representing incompletely articulated clasping 
organs. No distinctly developed incubatory plates. Pos- 
terior division of body without any kind of appendages 
whatever. 
The male of a similar appearance to the male in the 
genus Phryxus, with a distinctly segmented body, 7 pairs 
of clasping legs, and a non-articulate abdomen. 
Parasites, on lower organized Podophthalmata (Schi- 
zopods). 
Remarks. — In the strictly symmetrical body of the 
female and the absence of the 2 posterior pairs of legs, 
this genus agrees with Kroyers genus Dajus (Leptophryxus, 
Buchholz), but differs essentially, among other characteristics, 
in the deviating structure of the abdomen and the absence 
of true incubatory plates. The species live parasitically, as 
does Dajus mysidis, on lower organized Podophthalmata 
(Schizopods) ; but, while the former are invariably found 
enclosed within the incubatory cavity of Mysidians, the species 
belonging to the genus treated of here live freely attached 
to the dorsal side of the animal on which they subsist 
(hence the generic designation). 
Exclusive of the form described more particularly 
below, I have taken off our coasts 2 other distinct species, 
