CLASSIFICATION OF THE BRACHIOPODA. 



63 



Geological range. — Terehratulce with short loops are known to have lived from the 

 Devonian epoch to the present day ; they probably occurred likewise in the Silurian era, 

 although no positively authenticated example has been ascertained. 



Examples : T. vitrea, Gmelin, ?,^. grancUs, Blum. ; ampulla, Brocchi ; bisinuata, Lamarck ; 

 carnea, Sow.; obesa, Sow.; depressa^ Lamk. ; biplicata, Brocchi, sp. semiglobosa, Sow. ; Har- 

 lani, Morton, sella, Sow. ; insignis, Schiibler ; maccillata, Llhwyd ; globata, Sow. ; perovalis, 

 Sow. ; Kleinii, Lamk. ; simplex. Buck. ; spJiaroidalis, Sow. ; plicata, Buck. ; fimbria, 

 Sow. ; diphya, Columna, '&'^.flahellum, Def. hastata, Sow. ; elongata, Schl. ; coarctata. Park ; 

 longirostris, Walh. ; &c. &c. 



Section A, sub-genus — Terebratulina, D'Orb., 1847.^ 



Type — T. caput-serpentts, Linn. sp. 1767. Introd., PI. VI, figs. 7-8. 



Anomia and Anomites, (part) oi Linnceus, Chemnitz, Wahlemberg, &c. 

 Terebratula, (part) of the generality of Authors. 

 Terebratulina, IfOrhigny. 



Shell, generally longer than wide, and more or less oval ; beak obliquely truncated by 

 a foramen, which generally extends to the umbo ; deltidiura small, and at times in- 

 distinct ; socket or dorsal valve less convex than the perforated one, exhibiting two 

 variably developed auricle expansions. Surface striated or costellated. Valves articulating 

 by means of teeth and sockets ; loop short, not exceeding one third of the length of the 

 shell, and rendered annular by the union of the oral processes in the shape of a shelly 

 band. The cirrated arms are supported by the crura and project considerably into the 

 interior of the shell ; structure punctated. 



Obs. The species comprised in this sub-section are intimately allied to Terebratula, 

 but differ in the union of the crural processes, which form a shelly band behind the 



mouth of the animal, whereas the reflected 

 border of the loop is always in front (below 

 in the figure) of the mouth. In young 

 examples of the recent T. caput-serpentis, the 

 crural processes are not completely joined, 

 showing an intimate relation to Terebratula 

 proper. The disposition of the cirrated 

 T. caput-serpentis. ^rms appear the same as in T. vitrea and 



4. Dorsal valve of a youna specimen, in which its oral vro- iTT 4. T ix. 'i i i 



cesses are not yet completely developed. ^^' aUStrollS ; they are UUltcd by a mCm- 



5. Shell with the animal: the intestine is seen projecting braUC, and aSSUmC the form of tlirCC lobeS, 



above the oral aperture and fringe, the (esophagus passes , i i i i • 



through the annular part of the loop. the Central lobc being roUcd up like the 



' Considerations Zool. et Geol. sur les Brachiopodes, Comptes rendus de I'Acad. des Sciences, 1847; 

 and Pal^ont. rran9. Ter. Cretaces, vol. iv, p. 56. 



Fig. 4. 



Fig. 5. 



