172 W. Lilljeborg on the Genera Peltogaster and Liriope. 



The skin is very delicate, smooth, and very transparent. The 

 organ of adhesion is placed behind the middle of the body. It 

 is very small, furnished with a very short neck, and with mar- 

 gins which are but little folded outwards, and scarcely radiated. 

 The colour is the same as that of the skin, which forms, as in 

 the preceding species, an elevated ring round the organ of ad- 

 hesion. The anterior opening is scarcely visible ; it is not placed 

 at the middle of the extremity of the body, nor surrounded by a 

 a raised and folded margin. The colour is whitish-yellow or 

 light red. 



The young animal or larva (fig. 16), while enclosed in the 

 egg or just escaped from it, greatly resembles that figured by 

 Lindstrom. It is not yet sufficiently developed to enable the 

 germ of the antennae to be seen in the apophyses of the anterior 

 part of the body. Here we see only a streak formed of the same 

 material as the antennae. These apophyses were applied against 

 the margin of the body, and were visible only after strong pressure. 

 As found by Messrs. Spence Bate * and Darwin in the larvae of 

 the Cirripedes, they certainly issue in this larva from the lower 

 side of the body, as do also the antennae which are formed in 

 them ; so that they do not belong to the dorsal buckler. The 

 posterior part of the body usually wanted the two little promi- 

 nent parts of the lower surface which occur in the specimen 

 figured. They might therefore be regarded as a mark of a more 

 advanced development. The spot of pigment in the place of the 

 eye, being of a reddish-brown colour, can only be a rudimentary 

 eye. It has much resemblance to the eyes of the larvae of the 

 Copepoda. 



This species has been found on Pagurus chiracanthus and P. 

 Icevis on the coasts of Norway. It does not appear to be rare. 



With regard to the relation between Pachybdella and Pelto- 

 gaster, and between these and those Crustacea most nearly allied 

 to them, the author remarks that his descriptions prove that the 

 animals differ from each other so much as to belong not only to 

 distinct genera, but also to two distinct families. Pachybdella is 

 far higher in point of development than Peltogaster ; and in its 

 structure the former presents more analogy with the ordinary 

 Cirripedes than the latter. On examining the opened Pachy- 

 bdella (fig. 7), it is found to have a mantle or sac like the other 

 Cirripedes ; this sac surrounds the thick and fleshy body, which, 

 although much metamorphosed, presents some resemblance in 

 its form to that of the body {thorax) of a Balanide when all the 



* On the Development of the Cirripedia, Ann. .and Mag. of Nat. Hist. 

 2nd series* vol. viii. p. 324. 



