DE. T. DAVIDSON ON EECENT BEACIIIOPODA. 71 



Plate VII. 



Fig. 1. TerebratuUna [Agulhasia) Davidsuni, King: natural size. 1 a, 1 b, 1 f. Shell enlarged. 



Fig. 2. Ditto, interior of ventral valve, enlarged. 



Figs. 3, 4. Ditto, interior of dorsal valve and sectional diagram of same, enlarged. 



Fig. 5. Tubuli cliaracteristic of TerebratuUna caput-sei-pentis {1-d after King). (Davidson Collection, 

 Gcol. Dept., British ISIuseum.) 



Figs. 6-lt. Waldheimia flavescens, Lamarck, s]). ( = Terebratula australis, Quoy). Different specimens from 

 Port Jackson, N.S.W., showing modifications in shape and in ribbing. 10, (afterG. B. Sowerby), 

 shows the extent the animal opens its valves. 13, represents the var. recurva, Quoy, ft-om Shark 

 Point, Port Jackson. 12, 12 a. A young smooth shell, from Bottle and Glass Rocks, Port Jack- 

 son. All the specimens, with the exception of fig. 10, from the Davidson Collection, Geol. 

 Dcpt., British Museum. 



Fig. 15. Dorsal view of IValdhebnla flavescens, the .shell having been removed (after Hancock) . «, pallial 

 lobe ; b, body ; c, peduncle ; d, great inner pallial sinuses, giving off branches to the margin ; 

 e, outer ditto ; /, genitalia seen through the pallial membrane ; g, red matter of ditto ; /;, mar- 

 ginal fold ; i, seta; ; j, eircumpallial vessel ; k, extreme pallial margin ; /, median fissure, corre- 

 sponding to longitudinal plate in valve ; m, depression occasioned by the hinge-plate and the 

 bases of the crura ; n, orifices for the passage of the crura ; o, ridge formed by the union of the 

 pallial margins ; p, extremities of anterior occlusors ; rj, ditto of posterior occlnsors ; r, ditto of 

 divaricators ; s, ditto of dorsal adjustors ; t, liver seen through the wall of the body. 



Fig. 16. Ventral view of the same; the letters up to and including k correspond to those of fig. 15. 

 /, extremities of the occlusor muscles ; m, ditto of divaricators ; n, ditto of accessory divaricators ; 

 0, ditto of ventral adjustors; ;;, ditto of peduncular muscles; g, cjecal extremity of intestine, 

 seen through the wall of the perivisceral chamber ; r, peduncular nerves. 



Fig. 17. Thin lamella of shell of Waldheimia flavescens (after Carpenter), showing the parallel disposition 

 of the flattened prisms, and the regular arrangement of the passages which intervene between 

 them ; and at a the outcrop of these prisms of the internal surface of the shell. Magnified 

 100 diameters. 



Fig. 18. Internal surface of Waldheimia flavescens (after Carpenter), showing the imbricated arrangement 

 of the extremities of the prisms, which are seen longitudinally at a. Magnified 100 diameters. 



Fig. 19. External surface of shell of Waldheimia flavescens (after Carpenter), showing the large trumpet- 

 shaped ends of the vertical passages, covered in by opercular disks, which have radiating lines 

 proceeding from them. Magnified 100 diameters. 



Note. — Figures of the dorsal and ventral valves, of the muscular system, and of the labial 

 appendages and animal of W. flavescens are given in the text at pp. 42, 45, 47, and 48 (woodcuts, 

 figs. 3, 4, 5, G, 7, & 8). 



Plate VIII. 



Fig. 1. /r«W/(t'm/a wwo*«, Solandcr, sp. Type. (See Dixon, ' Voyage round the World,' 1789.) From 

 Falkland Islands. 



Figs. 2-2 c. Waldheimia venosa. The largest specimen known, dredged alive in Stanley Harbour, 

 Falkland Islands, by Admiral B. J. Sulivan in 5 or 6 fathoms, 1844. 



Fig. 3. Widdheimia venosa. Type of the Terebratula globosa of Lamarck, which was badly figured in 

 the Encyclopedic Methodique, pi. 239. fig. 2, 1789. (Museum d'Histoire Naturelle, Paris.) 



Fig. 4. Ditto. Type of the Terebratula physema, Valenciennes, after Reeve's figure, ' ^Monogr. of Tere- 

 bratula, Conch. Icon.' pi. vi. fig. 23. From Cocpiimbo. (Museum d'Histoire Naturelle, Paris.) 



Fig. 5. Ditto. Interior of the dorsal valve of a full-grown specimen, to show the loop. 



Fig. G. Ditto. Type of the Terebratula Fontaineana, A. d'Orbigny, ' Voyage dans I'Am^rique Meri- 

 dionale,' vol. v. pl. 85. figs. 30 & 31, 1847. (Reduced f natural size.) From Coquimbo. 



