BRACniOrODA 



363 



il, are found in tlio Upper Oolito and tlirougliout tlio Chalk 

 fiories and London Clay.* 



Family I. — Terebratulid^. 



Shell minutely punctate ; usually round or oval, smooth or 

 striated ; ventral valve with a prominent beak and two curved 

 hingo-tceth ; dorsal valve with a depressed umbo, a promi- 

 nent cardinal process between the dental sockets, and a slender 

 shelly loop. 



Animal attached by a pedicle, or by the ventral valves ; oral 

 arms united to each other by a membrane, variously folded ; 

 sometimes sjiiral at their extremities. 



A 



B 



Fig. 147. Terehratula viirca, Bom. 



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



Etymoloijy, diminutive of terehratus, perforated. 



Synonyms, Lampas, Humph. Gryphus, Muhlfeldt. Epithyris, 

 rhii. 



Types, T. maxillata, PI. XV., Fig. 1. (= Ter. minor-sub- 

 rubra, Llliwj^d. Anomia terebratula, L.) T. vitrea, Fig. Ii7. 



Hihell smooth, convex; beak truncated and perforated; 

 foramen circular ; deltidium of two pieces frequently blended ; 

 loop very short, simple, attached by its crura to the hiuge-plato 

 (Fig. H7, A). 



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

 lobe elongated and spirally convoluted (l*'ig. 147, B). The 

 young of T. diplnja (I'ygopo of Link) has bi-lobed valves 

 (PL XV., Fig. 2) ; when adult the lobes unite, leaving a round 

 hole through the centre of the shell. 



• The author lias to acknowloilgc his obligation to Mr. Davidson for (he use of 

 the notes, (h-awings, and specimens, assembled during the preparation of liis great 

 work on the " Britisli Fossil ]>rachiopoda,'' printed for the Palseontographical 

 Society; to which work the student is referred for more copious descriptions aud 

 lllustr&tions. 



u2 



