PLATE VI. 



The following Letters refer to the same parts and impressions in every figure. 



A, adductor muscle {add. longus, Owen) ; r, cardinal muscles {add. brevis and cardinalis, Owen) ; 

 p, pedicle muscles (retractor sup. and inf., Owen); j, cardinal process; l, loop; T, teeth; 

 B, sockets ; D, deltidium ; v, vascular impressions ; 0, ovarian spaces ; s, septum, ^c. 



Fig. 



1 . Terebratula vitrea. Loop only once attached, and short. 



2. „ „ Interior of dorsal or socket valve. 



3. ,, diphya. Type of the genus Pygope of Link, antinomia of CatuUo. 



4. 5, 6. „ elongata (5 loop), 6 is a portion of internal cast, shewing the place of the dental 



plate, X. 



7. Terebratulina caput serpentis. 



8. ,, ,, Interior of dorsal valve. 



9. Waldheimia fiavescens, Lam. {australis, Quoy), type of Professor King's section. 

 10- „ „ Interior of dorsal valve. 



1 1 . Terebratella chilensis. Type of M. d'Obigny's section. 



12. „ „ Interior of dorsal valve, shewing the double attachment of the loop. 



13. „ ,, Section to exhibit the septum, s. 



14. „ Evansii. Section to shew the largely developed septum, s, in this species. 

 l.T, 16. Trigonosemus elegans, Koenig = Fissurirostra, D'Orbigny. 



17, 18. Terebrirostra lyra. 



19. Magas pumila. 



20. „ ,, Interior of dorsal valve. 



21. ,, ,, Section of both valves, to shew the largely developed septum, s, &c. 



22. Bouchardia tulipa, Blainv. := rosea, Mawe, &c. 



23. ,, „ Interior of ventral or dental valve. 



24. • „ „ Interior of dorsal or socket valve. 



25. „ „ ^ Section of both valves. 



26. Megerlia truncata. 



27. „ „ Interior of dorsal valve. 



28. Kraussia rubra, Pallas, sp. 



29. ,, „ Interior of dorsal valve. 



30. MoRRisiA ANOMioiDES, Scacchi, sp. = T. appressa, Forbes. Exterior, o, ovarian impressions, 



V, labial appendages seen through the translucent shell. 



31. „ „ Interior of c?or5a^ or «oc^e< valve, shewing the large notch for the passage of 



the peduncle in this valve. 



32. Argiope decollata. 



33. „ „ Interior of dorsal valve, shewing 5 ridges, z, and the position of the loop. 



34. „ Neapolitana. Interior of dorsal valve, as an example where the loop is only bilobed, one 



septum or ridge only existing. 



35. 36. Thecidium radiatum, Def., type of the genus. This species was attached by a small portion only 



of the extremity of the beak. 

 37. „ „ Interior of dorsal valve, z, dissepiments ; l, apophysary ridge for the 



support of the arms and brachial membrane ; w, bridge-shaped 

 process. 

 Interior of ventral valve. 

 Interior of dorsal valve. 

 Ditto. 

 Ditto. 



18 



38. 



>) 



,, 



39. 



19 



hieroglyphicum 



40. 



)> 



digitahim. 



41. 



I> 



hippocrepis. 



