BUACHIOPODA. 



217 



Fig. 116. Ter: Evansti-Bav. 



Terebratella, D'Orbigny. 



Tf/pe, T. dorsata, Gmel. (= Magellanica, 

 Chemn.) PI. XV. fig. 7. Rg. Ho. 



Shell smooth or radiately plaited ; dorsal valve 

 longitudinally impressed; hinge-line straight, or 

 not much curved ; beak with a flattened area on each 

 side of the deltidiuni; foramen large; deltidium 

 incomplete ; loop attached to the septum (s). 



Animal like Terehratula ; the spiral lobe 

 of the brachial disk becomes very diminutive 

 in some species, and is obsolete in Morrlsia 

 and T. Cumingii. Distr. excluding sub- 

 genera, 16 sp. Cape Horn, Valparaiso (90 

 fms,), New Zealand, Japan, Ochotsk, Spitz- 

 bergen, Labrador. Fossil, 16 sp. Lias — . 

 U.S. Europe. In T. crenulata and Evansii 

 (fig. 116) the dorsal septum sometimes pa-ojects so far as to touch the oppo- 

 site valve, but in other examples it remains undeveloped. {Davidson.) 



Sub-genera. Trigonoseinus (elegans) Konig. Si/n^. Delthyridaea (pecti- 

 niformis) M'Coy. Fissirostra, D'Orb. Ex, T. Palissii, Pi. XV. fig. 8. 

 Shell finely plaited, beak prominent, curved, with a narrow apical foramen ; 

 cardinal area large, triangular ; deltidium solid, flat ; cardinal process very 

 prominent. Bistr. 5 sp. Chalk, Europe. 



Lyra (Meadi) Cumberland, Min. Con. 1816. PI. XV. fig. 6. Syn. Te- 

 rebrirostra, D'Oi-b. Rhynchora, Dalman.* Shell ornamented with rounded 

 ribs; beak very long, divided lengthwise internally, by the dental plates; 

 loop doubly attached ? Distr. 4 sp. cretaceous : Europe. Three species of 

 similar form are found in the Trias of St. Cassian. 



Magas (pmnila) Sby. Fig. 117. Shell _ 



smooth, conspicuously punctate, dorsal valve 



impressed, foramen angular, deltidium rn- / ""^R^ \ / AW /rW Z 

 dimentary; internal septum {s) promi- 

 nent, touching the ventral valve; re- 

 flected portions of the loop disunited (/). 

 2 sp. U. Green -sand — Chalk. Europe. 

 The recent Ter. Cumingii, of New Zealand, Fig. 117. M.pumila.f 



* The name Rhynchora was given by Dalman to the Ter. costata. Wahl. (= T. 

 pectinata, L.) on the supposition that it was identical with Sowerby's P. Lyra; and as 

 no specimen could be found withalong beak, an artificial one was manufactured for 

 it, of which there is a cast in the Brit. M. The second species of " Rhynchora." Ter. 

 itpatulata, Wahl. has no beak whatever : in shape it is like an Argiope, but measures 

 an inch each way. The ventral valve is a simple bent plate with the teeth at the 

 angles ; the dorsal valve is flat,, with a very wide hinge-plate, and sockets at the angles^, 

 whilst a single septum projects from the centre, with po-rlians of. a loop attached. 



