BBACHIOPOBA. 215 



extend through a whole " system" of rocks, and abound equally in both 

 hemispheres ; others (like Spirifera striata) range from the Cordillera to the 

 Ural mountains. One recent Terebratula {caput-serpentis) made its appear- 

 ance in the Miocene Tertiary ; whilst others, scarcely distinguishable from it, 

 are found in the Upper Oolite, and throughout the Chalk series and London 

 Clay.* 



FAMILY I. TEREBRATULID.E. 



Shell minutely punctate ; usually round or oval, smooth or striated - 

 ventral valve with a prominent beak, and two curved hinge-teeth ; dorsal 

 valve with a depressed umbo, a prominent cardinal process between the dental 

 sockets, and a slender shelly loop. 



Animal attached by a pedicle, or by the ventral valve : oral arms united 

 to each other by a membrane, variously folded ; sometimes spiral at their 

 extremities. 



Fig. 111. Terebratula vitrea. Born. 

 Terebratula, (Llhwyd.) Brug. Lamp-shell. 



Mym. Diminutive of terehratus, perforated. 



Stjn. Lampas, Humph. Gryphus, Muhlfeldt. Epithyris, Phil. 



Types, T. masillata, PI. XV. fig. 1, (= Ter. minor- subrubra, Llhwyd. 

 Anomia terebratula, L.) T. vitrea, fig. 3. 



Shell smooth, convex ; beak truncated and perforated ; foramen circular ; 

 deltidium of two pieces, frequently blended ; loop very short, simple, attached 

 by its crura to the hinge-plate. (Fig. Ill, A.) 



Animal attached by a pedicle ; brachial disk tri-lobed, centre lobe elon- 

 gated and spirally convoluted. (Fig. Ill, B.) The young of T. dlphya 

 (Pygope of Link) has bi-lobed valves, (PI. XV. fig. 2.) ; when adult the 

 lobes unite, leaving a round hole through the centre of the shell. 



Distr. 1 sp. Medil. 90 — 250 fathoms on nullipore mud. {Forbes.) 



Fossil, 100 sp. Devonian — . World-wide. 



* The author has to ackowledge his obligation to Mr. Davidson for the use of tht- 

 notes, drawings and specimens, assembled during the preparation of his great work 

 on the British Fossil Brachiopoda, printed for the Palaeontograpliical Society ; t(. 

 which work the student is referred for more copious descriptions and illustrations, 



L a 



