164 W. Lilljeborg on the Genera Peltogaster and Liriope. 
and here it is attached to the inner surface of the skin (pallium). 
Except at this point, the body is everywhere surrounded by the 
external ovaries, resembling ramose ceca (fig. 7d). The 
structure of these resembles that of the external band-like ovaries 
described by Leuckart (Annals, ser. 3. vol. iv. p. 428, pl. 7. fig. 6) : 
according to Lilljeborg, they are contained in one, or perhaps 
two sacs formed of a delicate transparent membrane, which 
presents the appearance of an epithelium with irregular cells. 
The figure of the young animal given by Cavolini (copied in 
fig. 17) presents a closer resemblance to that of a newly-hatched 
larva of a Cirripede than that of Peltogaster, as observed by the 
author and Lindstrém. 
Sp. 1. Pachybdella Carcini, Rathke. (PI. IV. figs. 6 & 7.) 
Animal supra et infra leviter sinuatum; partes laterales obtuse ; 
acetabulum rhomboideum, marginibus simplicibus, non multum 
expansis. Color rufescenti-flavidus. Latitudo cire. 17—20, et 
crassitudo 9-12 millim. 
Peltogaster Carcini, H. Rathke, Beitrage zur Fauna Norwegens, Acta 
Leop. xx. p. 247, tab. 12. figs. 18, 19. 
Pachybdella Rathkei, Diesing, Syst. Helm. i. p. 435. 
It is found under the abdomen of Carcinus Menas, attached 
over the intestinal canal, usually singly, sometimes two together. 
Also met with on Portunus marmoreus, and, according to Steen- 
strup, on Portunus hirtellus im the Mediterranean. Lovén has 
met with it on the abdomen of a Hyas. 
The author adds that it is probable there may be several spe- 
cies of the genus, and, judging from Cavolini’s figures, that he 
had more than one species under his eyes. 
[As Leuckart has indicated (/. c. p. 424), the generic name 
Pachybdella must be changed to Sacculina, Thompson, and the 
species above described will stand as Sacculina Carcini, Thomp- 
son. We have also to add the species, Sacculina inflata, described 
by Leuckart.] 
Genus Peirocastrer, Rathke. 
Reisebemerkungen, Neueste Schrift. der Naturforsch. Gesellsch. 
in Danzig, ii. p. 195; Beitr. z. Fauna Norw., Acta Leop. xx. 
p. 244. 
From his observations on several new species of this genus, 
the author gives the following character for it :— 
Animal e Crustaceorum classe et Cirripediorum subclasse, ecto- 
parasiticum, in abdomine Paguri degens. 
Animal adultum. Corpus sacciforme, elongatum, teretiusculum, vel 
depressiusculum, cute (pallio) plus vel minus pellucida sed firma 
obtectum, minime segmentatum, et partibus appendicularibus arti- 
