298 EXPLANATION OF THE PLATES. 



23. Nautilus Pompilius, Linn. Septum with central si- 



phuncle, . . . . . . . . . 34 



24. Clymenia striata, Miinster. With internal siphuncle, 34 



25. Hamites cylindraceus, Defrance. With external si- 



phuncle, ......... 34 



26. Groniatites sphsericus, Sowb. Section. Carb. limestone, 



Bolland. a, aperture ; &, body-whorl ; c, suture, . 24 

 21. Ammonites obtusus, Sby. Lias, Lj^me Regis, a, aperture; 



6, body-whorl ; c, suture, ..... 34 



28, 29. Ammonite, showing the position of the lobes and 



saddles. Z>, exterior lobe ; iy, superior lateral lobes ; 



L\ inferior lateral lobes ; F, interior lobe and its arms ; 



a, auxiliarj^ lobes ; rf, exterior saddle ; ^, lateral 



saddles ; u, interior saddle, . • . . . 34 



30. Univalve spiral shell, with the parts named, . . 44 



31. Left valve of C^^therea chione, Linn, /i, ligament; u^ 



beak ; Z, lunule ; e, cardinal tooth; ^, t' ^ lateral teeth ; 

 a, anterior adductor impression ; a', posterior 

 adductor ; p^ pallial impression ; s, sinus of retractor 

 muscle of siphon, ....... 55 



32. Pecten varius, Linn, a, adductor impression ; m, pallial 



line ; Z, ligamental margin ; c, cartilage ; e, anterior 

 ear; 6, byssal sinus, ...... 56 



33. Ammonite, with apt^^chus, . . . . . . 38 



34 to 38. Forms of opercula; 34, claw-shaped ; 35, lamellar; 



36, multispiral ; 37, paucispii'al ; 38, articulated, . 51 



Plate 3. 



39 Spicules in the integument of Doris pilosa, Linn., . 12 



40. Mytilus edulis, Linn. Showing the foot, byssus, and 



attachment, and branchiae. (Meyer and Mobius), 61, 110 



41. Dreissena polymorpha, Pallas. /, foot; 6, byssus, 61, 110 



42. Clausilia Macarana, Ziegler, magnified, and broken to 



show the clausilium, c, and the columellar axis, a. 

 (Fischer), 61 



43. Dentalium Tarentinum, Lam., animal, with the shell 



removed. Z, foot ; d, anterior mantle opening ; a, 

 posterior opening ; r^ kidney ; /, liver ; gr, genital 

 gland. (Lacaze-Duthiers), .... 66, 105 



44. Tegumenta of Tebennophorus. i, mucous lamina ; ^, 



muscular lamina ; 3^ peritoneum ; ^, visceral cavity ; 

 J, pulmonary chamber ; 5, interval between the two 

 muscular layers, . . . . . . . 11 



45. Phasianella bulimoides. Lam., . , . . . 14 



46. Oliva maura, Lam. x^ filiform appendages of the 



mantle; ^-j siphon. (Keferstein), . . . 13,14 



