64 



INTRODUCTION. 



proboscis of a butterfly. The animal in this sub-section was well figured by Godfroy 

 Auguste Griiiidler, of Halle, in 1774/ as mentioned both by Cuvier and V. Buch. Apart 

 from the peculiarity of the loop, the Terebratulina form a small group so well characterised 

 by form and sculpture as never to be confounded with any other. The beak is truncated, 

 and the foramen partly encircled by a deltidium united or disunited in difierent species. 

 The ear-like expansions on the sides of the umbo are also characteristic of this sub-genus. 



Geological range. — In our present knowledge the first species appeared in the Oolitic 

 period, and continued under difierent forms to the present day. 



Examples ■• T, capiit-serpentis, Linn. sp. ; japonica, Sow. sp. ; cancellata, Koch, sp. ; 

 Cumingii, Dav.; striatula. Sow. sp.; lacryma, Morton, sp.; s^na^a, Wahl. sp. ; (7wn', Hag. 

 sp.; Martiniana, D'Orb. ; gracilis, Schl. ; echinulata, D'Orb. ; subsiriata, Schl. sp. ; &c. 



Section B, sub-genus — Waldheimia, King, 1849.^^ 



Type — W. AUSTRALis, Qwoy and Gam., sp. Int., PI. VI, figs. 9, 10. 



Anomia, (part) Columna, Idnnceus, ^c. 



Terebratula, (part) Llhwyd, Lamarck, Brug., Dav., and the generality of Authors. 



Lampas, (part) Humj)h. 



Waldheimia, King, Gray, ^c. 



Terebratula, with long Loops, Dav. 



Shell, variable in shape, more or less circular sub-quadrate, transverse or elongated, 

 with both valves convex, or with the smaller or dorsal one depressed or concave ; margins 

 straight or waved ; surface smooth or plaited ; beak truncated and perforated by a circular 

 foramen of variable dimensions, partly completed by a deltidium in one or two pieces. 

 Loop long, in general exceeding two thirds of the length of the valve, formed of 



slender shelly riband-shaped lamellae simply at- 

 tached by the crura to the hinge plate, and more 

 or less folded back on itself. The cirrated arms 

 are partially supported by this appendage, and 

 united throughout by a membrane, exactly as in 

 the typical species of Terebratula. The valves 

 articulate by means of teeth situated one on each 

 side of the deltidium, supported by plates, and 

 fitting into corresponding sockets in the smaller 

 or dorsal valve. In the interior of the smaller 

 valve, a prominent cardinal process or boss, and 



vressions; V), pedicle muscles; x, accessory car- i • „i j. •i.\ c ^ • • ^.^ 



' '^ the hmge plate, with torn' depressions, occupies the space 



between the socket ridges, under which originates 



Fig. 6. 



Fig. 7. 



f. 6, Dorsal valve; j, cardinal process or boss; t', den- 

 tal sockets; p, hinge-plate ; s, septum; c, crura 

 of the loop; 1, reflected portion of loop; m, quad- 

 ruple adductor impressions. 



f. 7, Ventral valve; {, foramen; d,deltidium; t, teeth; 

 a, adductor-impression; r, cardinal muscular im- 



dinal muscles; v, vent; z, attachment of 

 peduncle-sheath (capsularis, Owen). 



^ Naturforscher, i, 2d part, p. 86, tab. iii, figs. I, 6. 



^ A Monograph of English Permian Fossils, p. 143, 1849. 



