W. Lilljeborg on the Genera Liiiope and Peltogaster. 53 



parvulum carnosum, ovaria interna continens, et tubulis oviferis 

 ceeciformibus ob tectum, videmus. 



Clistosaccus Paguri, n. sp. 



Specimina duo, quorum majus (fig. 5) 5 millim. longum in abdo- 

 mine Paguri Bernhardi, mense Julii ad litus Bahusiee accepta. 



Peltogaster Paguri, Eathke. 



The outer membrane of the pallium is composed of two chiti- 

 nous lamellae, of which the exterior is the thickest, and has more 

 or less distinct longitudinal lines or bands, somewhat resembling 

 those occurring in the membrane enveloping the ovarian sac. 

 The development of these bands varies upon different parts of 

 the pallium, and the lamella itself is from time to time of dif- 

 ferent degrees of thickness and opacity. On the inner face of 

 the interior and more delicate membrane there is a more or less 

 distinct epithelium with irregular cells ; and this lamella itself is 

 sometimes composed of hexagonal cells. The epithelium is more 

 distinct between the bands. Within this lamella, and slightly 

 attached to, or sometimes separate from it, there is a membrane 

 or thick and more or less opake sac, of cellular and fibrous struc- 

 ture. It consists of a thick cellular layer, upon the inner face 

 of which there are bundles of muscular fibres feebly bound to- 

 gether and directed transversely. These fibres are naturally 

 formed from the cellular layer, and in P. sulcatus the author has 

 seen these cells taking the form of fibres, which are striated, 

 whilst in P. Paguri they are smooth. In the cellular layer 

 there is a system of lacunar canals, but less developed than in 

 Apeltes. 



This membrane answers exactly to the second membrane of 

 the pallium in Sacculina, and the author therefore regards it as 

 belonging to the pallium, although, when the Peltogaster con- 

 tains no ova, it is sometimes contracted, and forms a sac con- 

 siderably removed from theouter membrane (PI. III. fig. 2d). It 

 extends into the anterior orifice of the pallium, where it is very 

 thick and abundantly furnished with muscular fibres which act 

 as sphincters. It is probably this sac that was regarded by 

 Rathke as an organ of digestion or stomach, and at the same 

 time as a matrix. The author described its membrane as the 

 " dermis " in his previous memoir. 



When these membranes are removed from the animal con- 

 taining ova, its lower surface presents the appearance shown in 

 PI. II. fig. 8*. Along the median portion there is a whitish or yel- 

 lowish body (the ovarian sac), which is bordered above and along 



* The specimen figured was preserved in spirit. 



