W. Lilljeborg on the Genera Peltogaster and Liriope. 265 
analogy of Bopyrus abdominalis, Kroyer, may readily be ascribed 
to difference of age, and perhaps of sex. The young animal 
described by the author was only one-twelfth the size of that 
described by Rathke. The latter is more elongated, and has 
one more pair of thoracic feet; the first pair of antenne are 
furnished with several sete; most of the thoracic feet are 
apparently shorter; the abdominal feet are a little shorter; 
and the caudal feet are differently constructed, being simple, 
while the young observed by the author have them biramose. 
But these and some other differences occur also between the 
young male of Bopyrus abdominalis figured by Kroyer and the 
still younger larve of the same species. Hence the author 
does not hesitate to consider the parasitic Isopod found by 
him upon Peltogaster Paguri as belonging to the same species 
as Liriope pygmea. 
Now, as it lives parasitically upon Peltogaster Paguri, its pre- 
sence in the cavity of the latter, where it was found by Rathke, - 
is explained without much difficulty. The Peltogaster may have 
borne a fully developed female Liriope, which, after reproduc- 
tion, had fallen off, whilst some of the young may have remained 
behind upon the Peltogaster, and walked about until, finding 
the orifice at the anterior extremity of the body, they en- 
tered by it; or they may have been in search of young females 
upon the Peltogaster, and remained attached to the’latter, just 
as Kréyer found a male of Bopyrus attached to the eye of a 
Hippolyte on which there was no female. The author is in 
favour of the latter opinion, as he thinks that if a mature female 
of Liriope had detached itself from the Peltogaster, the marks of 
its adhesion could not have escaped Rathke’s observation. 
With regard to the systematic position of Liriope, Rathke 
was eyidently wrong in considering it as an Amphipod ; and in- 
deed he indicates its “ resemblance to some Isopoda of the genus 
Idothea.” Dana was the first to recognize its lsopod nature ; he 
places it in the family Tanaide. Steenstrup asserts it to be an 
Isopod of the family Bopyride ; and his view of the relationship 
of Liriope, and its connexion with Peltogaster, is accurate. It is 
with the Bopyride that Prof. Lilljeborg arranges this singular 
genus, of which he gives the following character :— 
Genus Lirtore, H. Rathke. 
Animal e Crustaceorum classe, Isopodorum ordine, et Bopyridarum 
familia. 
Foemina adulta corpore in partes duas distinctas diviso; anterior 
sive cephalothorax, caput et tria segmenta sequentia comprehen- 
dens, est cum posteriore indivisa parte majore, sive matrice, quasi 
Ann. & Mag. N. Hist. Ser.3, Vol. vi. 18 
