126 



DESCRIPTION OF THE PLATES. 



Pl. XXVIII. 



Fig. 1. A single detached Echinococcus-head, with the hooks and suckers pro- 

 truded. The position of the six observed cilia is indicated by the wavy 

 lines. 



Fig. 2. A fragment of the Endocyst, with one of the abortive hooks. 



Fig. 3. Fully formed hooks from an Echinococcus-head, seen in profile and in 

 front. 



Fig. 4. Secondary cyst still attached to the wall of the primary. The external 

 Echinococci are seen in various stages of extension and contraction ; the 

 internal Echinococci shine through the walls of the cyst. 



Fig. 5. A similar cyst, with only one external Echinococcus. The relation of the 

 Endocyst to the laminated Ectocyst is well seen, and the budding Echi- 

 nococci on the inner surface of the former, which will eventually become 

 external heads of secondary cysts. 



Pl. XXIX. 



Fig. 6. A very smaU secondary cyst, with the remains of its pedicle above, and of 

 an external Echinococcus below. 



Fig. 7. Secondary cyst burst at the upper part and allowing three of the internal 

 Echinococci to escape. The contrast of their appearance vrith the two 

 dark and withered external Echinococci is well-marked. 



Fig. 8. Portion of the wall of a secondary cyst, showing the ramified vessels, and 

 the attachment of the internal Echinococci to its interior surface. 



Fig. 9. A large secondary cyst with no external head, but with the remains of its 

 pedicle appearing as a brownish spot. 



Diagrams: — Hypothetical representations of — A. a young Tania; B. a Ccenurus; 

 C. a Cysticercus ; D. the same, encysted; E. a Ci/stieercus, encysted, 

 enlarged, and developing many heads (like Coenu7~us) from the upper 

 portion of its outer (now inner) surface ; E. a similar form, which de- 

 velopes heads from the lower portion of its outer (now wholly outer) 

 surface, and so becomes an Echinococcus-cy&t. 



4. Descriptions of new species of Paludomtjs, a genus of 

 Freshwater Mollusks. By Lovell Reeve, F.L.S. 



1. Paltjdomus rudis. Pal. testa ohlongo-ovata, solidiuscula, 

 spira breviuscula; anfractibus superne leviter depressis, undique 

 obsolete costellato-striatis ; apertura subampla, intus callosa ; 



fusco-olivacea, immaculata, intus alba. 



Hab. ? 



A rather solid species, encircled with faint rib-like striae, and of a 

 uniform ohve-hrown colour. 



2. Paludomus trifasciatus. Pal. testa oblonga, spira sub- 

 elevata; anfractibus plano-convexis, undique costellato-striatis ; 

 apertura parviuscula, intus vix callosa ; olivacca, fasciis tribus 

 niffricanti-fuscis subirregulariter cingulata. 



Hab. Branch of the Ganges {Westermann) . 



It will be understood that the colour described in these species is 

 that of the epidermis ; the substance of the shell in all is of a bluish 

 white, faintly stained with the bands, which are more strongly marked 

 in the interior. 



