262 W. Lilljeborg on the Genera Peltogaster and Liriope. 
spot, no doubt indicating the mouth. Towards the base this 
part of the body becomes much narrower, forming a neck. No 
external buccal organs are visible. 
The posterior part of the body forms merely a matrix or ovisac. 
It is a reniform sac, convex above and below, with no impressions, 
folds, or sutures above, but furnished beneath with a longitudinal 
fissure (fig. 83) or aperture, through which the young escape. 
This part is of a reddish or flesh-colour, from the red ova and 
young shining through the transparent skin. At the point 
where the anus appears to be, there are some brown spots. 
During the contraction of the animal, some transverse folds ap- 
peared on the upper surface (fig. 1 a); these persisted when the 
animal was preserved in spirit, and perhaps indicate segments. 
At the posterior extremity of the fissure of the matrix is a round 
aperture ; no doubt, the anus. The skin of the matrix, although 
transparent, is firm and rather thick. 
Upon the cephalothorax, whilst the animal was still attached 
to the Peltogaster, there was a delicate and transparent pendant 
membrane, probably a cast skin. On the upper surface behind 
the neck there are an opake and thick skin and two areas of 
fibrous structure. The evolution of the valves, or the integument 
of the matrix, probably commences from these areas. The retro- 
grade metamorphosis in this animal is greater than in Bopyrus; 
there are no antennz, buccal laminze, feet, or branchial laminze. 
The Male. Prof. Lilljeborg did not detect the male upon or 
in the Peltogaster to which the female was attached, or upon the 
female herself. He thinks it very probable that the Liriope 
pygmea described and figured by Rathke was a young male. On 
comparing it with the description and figures of Krdéyer, repre- 
senting a younger male of his Bopyrus abdominalis*, which is 
the same as Phryxus Hippolytes of Rathke, the resemblance is 
striking. Kréyer’s young male Bopyrus was $ line, and Rathke’s 
Liriope scarcely 1 line in length. Thus, judging from their 
size, the latter was more developed than the former. The form 
of the body, the antennze, the legs, and caudal appendages, are 
very similar. There are some differences in the form of the 
posterior pair of thoracic feet ; but their structure is very charac- 
teristic, and conformable to that occurring in Liriope ; and this 
furnished the author with one of his best reasons for identifying 
the young of the animal found by him upon Peltogaster Paguri 
with Rathke’s Liriope. In Liriope Rathke found six pairs of 
abdominal feet, Kréyer only five in the young male of Bopyrus ; 
but Rathke has only four in his figure of Liriope, and the author 
found only five in the young of his species. According to 
* Naturhistorisk Tidskrift, Bd. 3. p. 291, tab. 1. figs. 21-24, tab. 2. 
figs. 1-3; Voyage en Scandinavie, pl. 29. fig. 1 t-w. 
