1868.] DR. J. E. GRAY ON THE SUID.E. 17 



lago interna, ossiculo magno curvato instructa ; Ugamentum 

 subinternum. Tmjjressiones nmscidaves conspiciice, posterior 

 magna, rotundata ; linea jjallialis sinuata. 

 This genus has much the appearance externally of Ixartia, Leach 

 (Rupicola, Fleur, de Bellv., not Brisson). The hinge is most like 

 that of PeripJoma, the ossicle being very large and strong ; but the 

 ligamental processes, although prominent, are without the strength- 

 ening ribs present in that genus, from which it also differs in the 

 beaks not being fissured. From the distorted appearance of the 

 shell, its habitat is probably in sponges or crevices of rocks. 



Pelopia brevifrons, H. Ad. (PI. IV. figs. 16, 16a.) fYfr,- 



P. testa solida, albida, iniBquiluterali, irregulariter concentrice 

 et rugose plicata ; latere antico breviore, rotundato, latere 

 postico angulato, margine superiore rectiusculo, inferiore ar- 

 cuato; sinu palliali lato, breci. 



Long. 14, alt. 13, lat. 8 mill. 



Hub. 1 {Coll. H. Adams). 



DESCEIPTION OF PLATE IV. 



Fig. 1. Stomatia variegata, p. 12. 

 2, 2«. Discus vorticella, p. 12. 

 .3. Nanina {Rohila) cernica, p. 12. 

 4. Pupa {Pupilla) exigtta, p. 13. 

 6. Cribhu.s {Chibbulma) mondraini, p. 13. 



6. {G-ibhulina) barclayi, p. 13. 



7. ( Gibbulina) productus, p. 13. 



8. 8 a, Tkyreopsis coraUiophila, p. 14. 



9. Macrochla'inys tenuicula, p. 14. 



10. 10 a. Glessula fusca, p. 15. 



11. Vitrina angasi, p. 15. 



12. Nanma {Xesta) sulcifera, p. 15. 



13. Gibbtis {^Gibbulina) clavulus, p. 16. 



14. Palaina coxi, p. 16. 



15. IHpIommatma minuta, p. 16. 



16. 16^. Pelopia brevifrons, p. 17. 



6. Synopsis of the Species of Pigs {Suidce) in the British 

 Museum. By Dr. J. Gray, F.R.S., V.P.Z.S., F.L.S. 



The distribution of Swine into species and the species into genera 

 and families is attended with considerable difficulty ; this probably 

 arises from three peculiarities of the group : — 



1 . That most of the wild or presumed wild species are easily re- 

 duced to a domestic or semidomestic condition. 



2. That the domestic breeds return to their wild condition, even 

 in countries situated far away from their native habitats, and that, 

 under favourable circumstances, the newly enfranchised animals are 

 able to hold their own against the native and colonial cultivators. 



Proc. Zool. Soc— 1868, No. IL 



